Plugins are crashing

Hi. I recently downloaded the NI Guitar Rig 4.2.2 update and my Cubase 6 has gradually been going haywire. First Guitar Rig just crashed Cubase every time I tried to open it, and now all my plugins are acting up, but intermittently: sometimes Alchemy won’t open, sometimes for Razor (etc) I get an error message such as “Error while reading file C:\Users\Public\Documents\Razor\Razor.rkplr: bad allocation”. Gradually I am losing all my plugins, and don’t know what has gone wrong. I tried uninstalling Guitar Rig but it didn’t fix the issue. I also tried contacting Native Instruments but they either don’t feel like answering or I’m in a queue two months long. Can anybody help?

I’m running a laptop with Windows 7 32-bit, 2.00 GHz processor and 3.00 Gb Ram.

Thanks.

Further to the above, I’ve just found out that it may help to rebuild the VST cache - does anyone know how I go about that in Cubase 6?
Thanks in advance.