Had a similar problem recently 

Last week my son picked up trojans/viruses from a dodgy gaming site.  With difficulty we eventually managed to delet the trojans.  However from then on IE kept crashing etc.

 

Same as you when I looked at runnung processe explorer.exe was using lots of memory all the time even when nothing was being done on the computer.

 

I ran avg/adware/spybot and nothing came up.

 

I then downloaded the new microsoft beta antispyware and it did pick some other things up which I deleted.  It also showed suspicious browser helper objects which it wouldnt let me delete.

 

However I did delete a file related to the BHO "glufxaoa.dll" which was located in system 32 file I think.

 

Now that was last week and my system is running very smoothly now and no more internet explorer crashes and no more detected trojans

 

Interestingly though today I updated AVG and ran a full scan, it found collected.2.ax trojan which was actually located in the recycle bin and it was infact the glufxaoa.dll that i had manually sent to recycle bin last week.

 

Hope this helps and maker sense!