Everything worked fine until yesterday evening. Now every few minutes or so ashServ.exe eats up 100% of my cpu to the point where my mouse pointer won’t move. I haven’t installed anything new yesterday. Trying to change the process priority in Task Manager failed. Help!
running on WinXP SP2
I suggest that you follow the debugging posted by Vlk here: http://forum.avast.com/index.php?topic=23283.msg193594#msg193594 
The issue mysteriously disappeared after I installed some unrelated stuff - Visual C#, DirectX, ATI and Nvidia SDKs, Blender and a few others. Avast was inactive while I was doing this. I suspect .net is accountable, but it’s just a wild guess. If the issue pops up again, I’ll make a dump and upload it. Thanks.