Since running System Mechanic I have had a few program freezes which all resolved themselves within 20 seconds and never required a reboot. Ultimately the situation seems to have improved, but is not completely resolved.
I am really liking Trillian so far, though Skype was not the cause of the problem here. The recent freezes I've had were opening Photoshop and hitting play on a video in Chrome.
To be perfectly honest with you, there are somethings in windows or your system that may go wrong you might never fix. :/
If its only a small minor performance issue just leave the machine alone and continue working.
Only time you fix it or reinstall windows if necessary, if things are majorly corrupt.
Your problems refuse to stop and it is a on going problem.
Let system mechanic run and scan while your not there.
It will evaluate your system and throw you some ideas to fix it or remedy the problem.
Deepscan is way much better than standard scanning.
Keep your system clutter free and error free if you use it all week long.