Start Up Problem

My harddrive recently had to be replaced. Since then, it had been working fine until the other day. When I went to start up, the normal blue screen with the apple logo came on, but it couldn't get passed that. If I leave it for about 5mins, the apple logo turns into a black crossed out circle...what does that mean? Do I need ANOTHER new hardrive now??
THanks for the help.

It means your machine can't find the startup disk or operating system. Boot the machine with your original install media. Escape from the install routine and select Disk Utility from the top menu. Run Disk Utility to verify the hard drive and post back the results.

Regards.

When I Verify Disk Utility, Three error come up:
-Invalid node structure
-Volume check failed.
-Error:Filesystem verify or repair failed

Any ideas?
THanks

looks like you put in a blank drive with no system on it, but you said you have used it so there actually is a system on there, right?

well, maybe not blank, but somehow damaged, not necessarily physically, maybe just permissions/ownership/missing os structure ...

did you fiddle around with anything like chmod and chown in the terminal?