Computer Lags at bootup and randomly freezes (BSOD)

[Tahiri]

Hi, my computer starts up fine and quick but as soon as desktop shows up the mouse starts to lag for about 10 sec and everything is generally slow.
After 10 seconds, everything works normally. This happens every time I log on/boot up.
Also noticed that in task manager, my BIOS time was shown incorrect (~7000sec) and also if the computer is idle for some time, it randomly freezes and restarts, sometimes(rare) showing the blue screen of death.
Tried scanning for viruses, malware and did the sfcscan too. The sfc scan picked something up and resolved it but still having the issue, no viruses,etc was picked up.
Also checked RAM and HDD.
PLz help if u know anything about this.

[Author Designs]

if you don't want to try a lot of fixes, there's a quick solution to that.. reinstall your os and it will prob fix that..
for me, if I encounter problems I try to troubleshoot it first, but if I feel lazy, I just reinstall the os and most of the time, it will fix the problem