Laptop Help...

So, I have an iBook G4 1.07 ghz, running 10.4.3.

About ten days ago, after returning home, I woke it up, and it froze. Apparently the hard drive had died ... couldn't be repaired. So I had it replaced with a Centron 60 gig HD at CompUSA.

Today, when I woke it up, it froze again. When I restarted, I got the dreaded flashing questionmark. I loaded the Tiger DVD, launched Disk Utility, and it didn't even see my internal HD!

After two restarts, I ejected the DVD, and everything loaded up just fine.

Any thoughts?