Are you using the same trial key or did you download a new one from MS?
As far as I know, only one Professional Plus Trial key can be installed on any given computer EVER. If you install a trial, use it, then uninstall Office and then go back to the Microsoft website and get a new key, the second installation will be rejected with an error message. Your problem may be related to that issue.
But try the following steps:
1) Delete the following keys from the registry (if exist):
2) Run the MS installer cleanup utility and remove Office 2010 entry (if any). Download from following link. http://download.microsoft.com/downlo...BD/msicuu2.exe
3) Navigate to the C:\Program Files folder and delete any Office folders.
4) Click Start button, type "%temp" without quotes and hit Enter. Clean out the temp folder.
Restart your computer, then try installing.