Check your CPU heat sinc is clean of dust, take the CPU FAN OFF(undo 4screws) there you will see a metal plate with panels, use a small fine paintbrush and clean between the panels if clogged up with dust.
check you are not covering any case vents that are blocking air circulation, you can also check your graphics card has not become unseated as sometimes if they get to hot they work loose.
Compaq Presario CQ5305K-m Intel® Pentium® Dual Core E5300 (2.6 GHz), Windows® 7 Home Premium 64 bit, 2048 MB , Hard drive: 320 Gb, with 18.5 Widescreen
SPURS TILL I DIE (DIAMONDS ARE FOREVER SO ARE SPURS)
TO DARE IS TO DO