Windows 7: Win7 works smoothly, then Suddenly slows down.

okay I just finished a scan. no infections

You ran the full MB scan? It should take at least an hour.

no I did the quick >_> starting the full

The full will give the correct answer.
If it is clean we can try a few more tricks.

I just finished a scan. the only result is a "trojan" which isn't really a trojan. I'm quite certain of that fact.

Just before the the time for the problem, do a clean boot and see if it happnes
How to See Who is Using Your Wireless Internet | eHow.com

Also download process explorer and notice what happnes at the magic hours. More ram being used, or is it just internet slowdown?

Our router is protected and secure. also its not the internet that is slow. its my actual computer.

The one thing I have noticed actually. Previous persions on my c drive seems to have "date modified" and all of the times listed are around the Zero hour for my problem.

Its software, probably the anti virus, Look at task scheduler, what is scheduled for that time?

Its a schedulded maintenance job.

Meant to give you the clean boot link above, sorry about that
http://support.microsoft.com/kb/929135

The clean boot will help, too. Use clean boot at the witching hour.

What am I looking for in the task scheduler? I don't see anything listed for the times where my slow downs occur.

so you recommend I start in safe mode an hour before the slow downs and see if they happen?

No not safe mode
Clean boot , I gave you the link

You are looking for the time in scheduler, if none there then that is not the problem.