6.51 Audio Pops & VST Crashes

I recently updated my Cubase 5 to 6.0 then 6.5/6.51. I hear a lot of random Audio Pops now I didn’t have in 5. Also, there seems to be an endless amount of crashes - most I suspect to be between VST3 and VST2 plugins - most notably BFD2. If BFD2 is active, I usually cannot load a new plugin such as Padshop. If I remove BFD2, ‘sometimes’ I can then add Padshop or similar. If I start a brand new track (not updated from 5.0), I can add Padshop etc but still random pops.

Have also trashed preferences etc. Any input on this would be great. I’m using XP and have 2 MR816 csx units on firewire.