@greg...I'm curious as to why you would suggest that the OP replace Avast with MSE when Avast uses less resources?
I still use Avast some too and consider it comparable to MSE but either can sometimes conflict so to check this I switch to the other. MSE is overall less problematic, too.
Remove Daemon tools app.
Try MSE in place of Avast. Use WIndows Firewall.
YOu have at least one tweaking utility. Win7 needs no tweaking whatsoever, as those of us who beta tested it found out the hard way over a year. It will always come back to bite you. If you tweaked anything other than normal system settings available to set in Win7, then either SysRestore or clean reinstall. It is that bad.
1.I need Daemon Tools for the 'Assassin's Creed''s .iso file. I can't launch the game at all if I dont have DT.
2.Removed avast.
3.No tweaking utility whatsoever. Just disabled some features which I don't need. (IE, Printer related things and stuff like that)
GameBooster, Advanced System Care and the RAM Booster sound like tweaking tools to me. Instead of replying that you want them as with GameBooster, uninstall them long enough to see how performance changes. Unforunately with tweaks, you'll only really know if you uninstall the tweaks by using the rollback function in the utility or SysRestoring back far enough. But tweaking is so problematic in Win7 that if this cannot be clearly done I recommend a rsinstall which often overcomes problems caused by unnecessary tweaking.
Try mounting your ISO with PowerISO which is more compatible. Or uninstall Daemon and use disk to check what changes.
If you are getting Blue Screen (BSOD) shutdowns then go to Crashes forum here and upload the bugcheck report it generates using the tool pinned to the top of page then post it there. They specialize in solving these.
TYpe Event Viewer into Start Search box, choose Admin view to google repeat errors to find how others have resolved them. This is how you troubleshoot problems.
I think he was referring to editing graphics effects at Computer>Properties>Advanced settings>Performance. If you choose Best Performance it will send you back to XP graphics, so you really only want to edit out fading, sliding, dragging intact windows, etc. as you experiment and find what's best.
Click through your WEI score on Properties page to access Advanced Tools page. Study Performance log there closely for repeat errors, look for issues cued at top of Tools page, then Generate a System Health Report.
Sometimes Catalyst should go the other way: Uninstall and use only driver if you don't need advanced settings it offers. This will solve some problems with Catalyst conflicts, and those who don't need card settings don't need the package anyway except for driver.
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but still, no luck 
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