I don’t know how that could be related to avast! alone but one thing crossed my mind. 4GB of RAM and 32bit version of Vista. Thats a no go. For problem free usage of 4GB you need Vista x64…
I know that Vista 32 can’t use 4GB but with the current RAM prices the second kit was a must
However I don’t see how the 4GB could possibly be responsible for the described effects…
One thing that changed besides MoBo/CPU is the harddisk which is the same as before but is now using an AHCI controller. I think I read somewhere about some users having troubles with AHCI under Vista…