Windows 7: Wierd windows 7 problem

So this is what happens...
its been about 2 weeks that when i power up my computer, windows doesnt function well. for example, i try to open on itunes it doesnt open up, or i right click on folders, apps they keep loading up but never load up. and also on this first power up when windows is booting up, at the windows logo loading, it takes about 2-3 min to get to the actuall windows,(its usually comes up between 7-13 second). so when this happens i have to restart my computer and everything would be fine.
Anybody knows what is this problem?
thank you

Anything that you have can be resolved and we wil help.

To make sure it is not a serious problem. Run your anti Virus

and

Download and run malwarebytes.

http://www.malwarebytes.org/mbam.php

If it is malware or wors a virus, we should take care of that first. Then we can disucss the next course of action

If the tests come up negative, there are several repairs we can try. Dont worry you are with friends now. We will not let you down

We can't help without your system specs - fill them in with HWInfo32.

1) Update all your drivers with the guide in my sig

2) Run sfc /scannow - this may fix it, the rest of the steps will verify it.

3) Defrag

4) Run chkdsk

5) Clean out the msconfig tab from bloated startup entries

6) Run Memtest86+

Also, if this is a desktop what is the PSU + cooling system?

thank you richc46 and Frostmourne for the concern
it is 99% chance that it could be some virus, i will try all the following you guys listed very soon and post up the results. thank you again for the concern.

and this is my desktop information meanwhile:
it is a desktop. this is my PC information
dualcore e8500 3.84ghz
8gb ddr2
nvidia gtx 285
power supply 700ghz, great fan on cpu (name is not on top of my head)

Before you run through the steps, underclok the CPU back to stock. Then, run the steps, and monitor your temps with HWInfo32.

did all the followings
malwarebytes found many bad guys, deleted them
and i did all the steps Frostmourne said, and now only time would say if my problems got fixed. i will reply in a short time to let you guys know, where is our progress.
thank you

I think that you will be ok. Wish you luck

i believe it is fixed. thanks alot dudes. appreciate everything.

We are all as happy as you are. Good luck.