PC not recognizing boot device

My old PC has been giving some problems lately. Somtimes, it freezes out of nowhere and when i restart, it tells me it did not find a boot device. I go into BIOS and check if it even detects my HDDs, and it doesnt. Is this a PSU issue? cuz if it is, im gonna order one right now (FPS 400watt)

my current PSU is some no name 250 watt that came from my old compaq

the PC is:

Intel P4 2.4ghz HT
768 MB Ram
128MB 9600Pro
DVD-RW
2HDD (40 and 160 giggers)
2 120MM fans with LED lights
250watt PSU

Yes (imo).
Do you have another PSU in the 300w you
can borrow somewhere to just see if it makes a diff?

i bought a 400Watt FSP (Fortron) PSU, will try it tmrw. guy delivered it today but i wasnt home >_<