From the uad website:
Known Issues – Mac and Windows
System sleep is not supported with UAD FireWire devices (Apollo and UAD-2 Satellite)
Cubase 7 is not qualified with this release
All plugins are working for me in cubase 7 so far.
Every project over 3 Gb crashes when introducing more than one UAD plugin in 64 -bit OS and 64 bit application.
It’s NOT a Cubase 7 specific issue. I get the same result in Nuendo 5.5.5 (64-bit version) with RAM hungry projects.
UAD is faking the 64-bit compatibility. It’s NOT working. Very suspect releasing the “so-called” 64-bit versions so close to their own deadline. The reason for me going 64-bit is having access to more RAM for sample libraries. It’s unusable in large projects. This is very dissapointing.
My substantial UAD plugin investment during last year was fueled by a belief and promise that this would work as promised. Bullshit. Fakers. Snake Oil from UAD. Just be warned before investing into the UAD platform.
Yes, I am angry and frustrated.
EDIT: Issue fixed.
Seems it’s NOT truly 64-bit, but some kind of fake hybrid (Copied from thread in Gearslutz):
“Yes, this is true, UAD plugins are not full 64 bit. {In Sonar, plugins stayed open after switching into track view, this happens with Bitbridge, but I can start playing project when I am in active plugin window, this is not possible in Bitbridge if plugin is 32 bit, so I think it is some kind of hybrid”
Hi all,
No problem for me too:
- Win 7 64bits
- 16 Go ram
- UAD-2 OCTO and v6.4.0
no problem here too with a (begining) project of 5,85 Go of memory used (for the moment) with more than 30 UAD plugins + 25 Slate VTM + 24 Slate VCC + 2 VCM + Lex MPX + 2x LX480 (for the moment) ! 
instruments used on instrument track are : BFD2 + 2x Stylus RMX + 5x Virtual Guitarist 2 (with Jbridge) + Lounge Lizard + 2x Kontakt (Strings) + 3x Omnisphere + Absynth + 3x FM8 + 3x Zebra
Make sure those of you having issues have Cubase pointing to the correct directory where the 64 bit versions of the UAD plugins reside. Both 32 and 64 bit versions of the UAD plugs get installed, so it is important that you set this up correctly. Hope this helps!
It worked!
Problem Fixed: Deleted all Uad plugs in: C:\Program Files\Steinberg\VSTPlugins\Powered Plugins folder and replaced them with the ones in the: C:\Program Files\Universal Audio\Powered Plugins\UAD-2 Powered Plugins.
Problem solved. Seems something is wrong with the UAD installer, installing 32-bit versions in the 64-bit folder.
Thanks!
Strange - the DLL files in C:\Program Files\Steinberg\VSTPlugins\Powered Plugins here are all 69kb pointers.
The actual plugins themselves are in C:\Program Files\Universal Audio\Powered Plugins\UAD-2 Powered Plugins
the installer goes where your registry tell !
OK. Didn’t know they were pointers! 
Nevertheless the workaround i did means I now can load UAD plugs in very memory-intensive projects…what a relief!
uad v6.4 works fine here and i have no interest in upgrading to 6.5 just for the demo’s and possible incompatibility .
Known Issues – Mac and Windows
System sleep is not supported with UAD FireWire devices (Apollo and UAD-2 Satellite)
Cubase 7 is not qualified with this release
Known Issues – Mac
(Cubase 32-bit only) When performing audio processing via Audio>Plug-Ins menu or region editor window, UAD plug-in controls may become unresponsive if the plug-in window is moved. To regain control if this occurs, close the plug-in window then reopen it. This issue does not exist in the 64-bit version of Cubase.
(Cubase 32-bit only) When performing audio processing via Audio>Plug-Ins menu or region editor window with UAD Direct Developer plug-ins, the UAD Toolbar cannot be used to load or save UAD presets. UAD presets can be loaded using the up/down arrow buttons in Cubase’s preset management tools instead. This issue does not exist in the 64-bit version of Cubase.
Windows 7 64-bit UAD plug-in support
If using a 32-bit version of Cubase/Nuendo, updating to UAD v6.5.0 is not recommended.
32-bit editions of Windows 7 are unqualified.
UAD v6.4.0 (and higher) installs both 32-bit and 64-bit versions of the UAD plug-ins. Although 32-bit or 64-bit UAD plug-ins can be used in different sessions, using both types in the same session is not supported.
After installing UAD v6.4.0 (or higher), the host DAW may need to be redirected to use the 64-bit versions of the UAD plug-ins which reside in a different directory than the 32-bit versions. After redirecting to the 64-bit directory, the UAD plug-ins may need to be rescanned by the host. The directories to use are:
64-bit UAD plug-ins directory:
C:\Program Files\Steinberg\VstPlugins\Powered Plugins\
32-bit UAD plug-ins directory:
C:\Program Files (x86)\Steinberg\VstPlugins\Powered Plugins\
Important: To ensure the mono (m) versions of the UAD plug-ins remain accessible, use the VST directories above
I was having same issue and called UAD for support they had me check file/installation structure of my plugins. Seems that there was more than one UAD folder when I deleted incorrect folders and rescanned the 64bit worked like a dream no issue in VEP5 or Cubase. UAD’s customer support is wonderful if you have issue just call them for help
Yes indeed…I cannot determine why this arrangement exists. This new install behaviour first appeared in UAD 6.4.0. I removed these small 69KB “wrapper/pointer” files from my VSTPlugin directory and replaced them with the actual plugin binaries from C:\Program Files\Universal Audio\Powered Plugins\UAD-2 Powered Plugins.
This appears to have solved my problems with Cubase 7 64bit crashing with high RAM projects using UAD plugins.
All UAD plugins appear to work as expected, so the purpose of these small 69KB files is not clear. What seems to be clear is that they are responsible for crashing Cubase 7.01 64 bit…(for me)
Hi all,
Just installed UAD v6.5.0 yesterday night, everything works fine for me with Windows 7 64bits and Cubase 7 64bits.
the supported version is out http://www.uaudio.com/support/uad/downloads.html?utm_source=UA+list&utm_campaign=3efe5f1fb7-6_5_2_Announcement_2_28_20132_28_2013&utm_medium=email
You mean “out”.
Known Issues – Mac and Windows
The demo period for UAD API 560 must be started from within the UAD API 560 plug-in window even if the “UAD API 500 EQ Collection” demo is started from the UAD Meter & Control Panel.
Cubase 7 is not yet qualified with this release
. Complete qualification of Cubase 7 is planned for a future UAD release.
cubase 7 is still not supported yet only cubase 6 , thats most probably because steinberg are still fannying around with the bugs in c7
I am using a UAD1 card with the last update for it which is 6.1 if I load Cubase 6.5 projects into 7.02 none of the plugins work they are all disabled I have tried everything and it’s a no go. Also when I close 7 I get the blue screen of death. If I load a brand new project window everything works and no problems. I would love to know how this one is going to be resolved otherwise I will have to stay with 6.5 for the projects am working on.