Speccy says you have two problems.
First it's getting too warm:
CPU
Intel Core i3 2350M @ 2.30GHz 72 °C
Sandy Bridge 32nm Technology
RAM
4.00GB Single-Channel DDR3 (9-9-9-24)
Motherboard
Dell Inc. 01HXXJ (CPU 1) 73 °C
Ideally this should be in the 50s. 73 is close to the temp where it will freeze up or where the video will go crazy.
Make sure you have it on a flat hard surface. Putting it on something soft like a bed can block the air vents and cause it to overheat.
Try speedfan
Download, save and Install it (Win 7 or Vista right click and Run As Admin.) then run it.
It will tell you your temps in real time.
Normally what happens is the interface between the fan and the heatsink gets clogged with dust. On most Dell's you can remove the panel that covers the fan with about 8 screws. Then unscrew the fan (but not the heatsink) and you can then use a small brush and a vacuum cleaner hose to remove the dust. If you need to remove the heatsink you will have to replace the thermal paste.
Second the hard drive is dying:
These attributes are not good even if they say Status Good. Seagate drives just don't hold up. I would clone the drive before something else happens. I recommend Western Digital (Black if you can afford it). Avoid Seagate - they are getting a horrible rep.
01
Attribute name Read Error Rate
Real value 0
Current 116
Worst 99
Threshold 6
Raw Value 0006B170A8
Status Good
07
Attribute name Seek Error Rate
Real value 0
Current 81
Worst 60
Threshold 30
Raw Value 0009D07BD3
Status Good
BB
Attribute name Reported Uncorrectable Errors
Real value 123
Current 1
Worst 1
Threshold 0
Raw Value 000000007B
Status Good
C3
Attribute name Hardware ECC Recovered
Real value 0
Current 116
Worst 99
Threshold 0
Raw Value 0006B170A8
Status Good