Swapped hard disk fails to work

[webdude]

One for the techys! I have two Dell Desktops and decided to cannibalise them to make one reasonably good spec machine. I took the large hard drive out of the lower spec machine and swapped it for the drive in the higher spec PC. I added 2Gb more RAM to the 'new' PC, just to complete the upgrade.

When I power up the 'new' PC, it fails to load the OS which is Win XP Pro, and gives me the option of going to the setup screen or starting in Safe mode. It will not start in safe mode, and after checking the system setup, I cannot see anything wrong with the startup parameters.

I have run the Dell diagnostics, and the new memory is working ok, and all other tests failed to reveal anything. To double check I put my drive back into the original machine and it booted into XP no problem.

The only real difference between the two PCs is that one has a Pentium CPU and the other a Celeron, in all other respects they are the same part from the memory capacity.

Can anyone suggest what could be wrong here.
TIA

[ChuckFickens]

you can only swap hard drives between exactly identical computers, if they have different CPU's they will very likely have slightly different motherboards in which case you will need to reinstall windows on both of them to get them to work.

[webdude]

Aw Chuck you have just gone and spoilt my day - I was afraid that might be the answer, I was hoping not to have to do a re-install, but thanks for the reply.

[ChuckFickens]

There is one thing you could try before a reinstall, though backup as if you were going to reinstall first because if it doesn't work the drive may no longer boot on the original computer.

With the drive in the computer it works goto the device manager and open each item, right clicking on all devices except the keyboard and mouse in turn and select uninstall (do not restart the computer if it asks you) once you have removed all of them shut the computer down and install the drive into the new computer and turn it on.

if you are lucky it will re-detect the correct devices on startup and work, if not you will have to reinstall, so nothing lost in trying :)

[webdude]

Thanks Chuck - I will go and give your idea a try - will let you know if it works. Thanks for that.