Can't figure out problem?

Hello!

Okay im having some problems with my PC. All these problems started about 2 weeks ago.
I built this PC myself almost 2 years ago and have yet to have any issues prior to this.

I'm just going to list everything,

- PC randomly resets displaying CPU OVERHEATING black screen Sometimes after reset i get a black screen failed to start CPU overheating screen

- Cleaned out pc, problem persisted.
I usually clean it out every month.

- Downloaded SpeedFan, indicated my pc is running idle at 70-87c. :O
- Checked bios, indicates my pc is running 50-60c, at startup. o.O

- Got new Silver wolf 5 thermal paste and reseated stock cooler.
Temps did not go down according to SpeedFan.

- According to SpeedFan everything else is running normal temp, just CPU overheating.

Other problems that might be relevant:

- Windows Explorer crashed anytime i clicked anything in start menu
Had to reset computer.

- Received several errors past two weeks,
- Memory error blue screen
- Page_Fault error blue screen
- Over heating error blue/black screen

- On startup, before windows 7 welcome, black screen with only cursor,
sometimes takes 1-3 minutes to load, loading Welcome screen/explorer.
Other times it never loads just remains black screen with cursor.

- Stuttering/lag in video games, where they slow/freeze for several seconds or crash.
(No video card errors though. GPU is running green temps)

- Firefox has been constantly resetting.

Can't figure out whats wrong, i did order a new CPU cooler that should hopefully arrive soon.
Newegg.com - COOLER MASTER Hyper 212 EVO RR-212E-20PK-R2 Continuous Direct Contact 120mm Sleeve CPU Cooler Compatible with latest Intel 2011/1366/1155 and AMD FM1/FM2/AM3+

Any help is greatly appreciated,
If you need a dxdiag or any other info just ask.