Upgrade to Snow Leopard does not see external drive

Yesterday I took my macbook pro to the apple store to have fans replaced. I also had them upgrade my OS to 10.6.3. Once home, I upgraded to 10.6.8. I have an external drive HP Pocket Media Drive model PD5000z. Prior to the OS 10.6.3 upgrade my external drive was working flawlessly with Time Machine. Now since the upgrade I cannot get the drive to be seen. It does not show up in the sidebar, Time Machine does not see not drive, etc.

I went into Disk Utility found my disk and tried the "First Aid" first. All the options at the bottom of the page, 'Verify Disk permissions', 'Repair Disk Permissions', 'Verify Disk', and 'Repair Disk' are grayed out and cannot be clicked on.

I next tried the "Erase" tab, and tried to erase this disk. I'm getting 'cannot allocate memory' when I click erase.

This drive has been working flawlessly for about a year under the Lion OS. Now I can't get anything working on it.

HELP.

Thanks,
Shirley

Lion would be 10.7 and has not been out but a couple of months did you mean Tiger?
Was the external drive encrypted if so that will keep you from doing anything till the proper password is entered.

osxx said:

Lion would be 10.7 and has not been out but a couple of months did you mean Tiger?
Was the external drive encrypted if so that will keep you from doing anything till the proper password is entered.

Click to expand...

Ooops, I meant Leopard not Lion. I upgraded from Leopard to Snow Leopard. The drive worked flawlessly for about a year under Leopard.

And, no, the external drive was not encrypted.

Thanks,
Shirley