Help - Grey Screen & Kernel Panic?

i own a 2.1ghz 2gig mac that has been upgraded to 4gigs by an authorized apple reseller. lately i had the 2-3 beep issues so i had my mac serviced and i was told by the technician that they couldn't find any problems so they felt that it was most likely a RAM issue. but since i need my laptop for assignments, the technician loaned me a 2g RAM to support it for the meantime. i just got the grey screen when i switched my mac on telling me to reboot with some foreign languages. from what i've read around, it could be a kernel panic. so i rebooted and i still got the same grey screen for maybe 2-3 times until i got tru the startup screen which is now.

could this be caused by the 2g RAM/insufficient RAM? or internal hardware problems because i was told by the technicians that they couldn't find any problems

btw i'm new to mac too.