Problem after windows start up

[amirhossssein]

hey there
im having this problem (for like at least 4 or 5 months now) that after i turn on the PC and windows is fully loaded i cant open any program for 40 or 60 secs
and sometimes the booting process (that logo page, i dont know what they call it) takes more than the usual time
and sometimes before all of this ,it will stuck right after turning on the pc in that page which says my Motherboard's company name
and sometimes after that page (motherboard's company name page) it will stuck in a completely black page
and when im working with some programs suddenly an error about Explorer.exe will apear and after hitting "Dont Send" every page will get closed (not programs , just My Computer and Drives and stuff)
and + i cant even play Dota , after like 5 minutes it will start lagging
my CPU is 5.2
Graphic is 1GB 9500 GT
Ram 2 Gig
and first i thought it's because of my CPU , then i installed some CPU monitoring program and it's results seemed normal
and i've tried re-installing the windows (installed an updated version) but didn't work
any thoughts would be appreciated thank u

 

[electronian]

That really sounds like a virus.
You might need to hire a qualified professional.

 

[amirhossssein]

That really sounds like a virus.
You might need to hire a qualified professional.

cant these anti virus programs do it ??
and i forgot to mention i don't have any Anti virus Installed in my pc
and i usually always have tons of Virus's in my system but they never bothered me that much , until now (if its a virus)
but gotta add this too , after i installed this "updated" version of windows XP , i did install a recent version of Bitdefender and ran a search (and found quiet a lot of virus's) and then uninstalled it