Not enough memory or disc space to run Word

I installed Microsoft Office home and Student 2007 on a new PC running Windows 7 last week. The installation worked and I was able to run Word and Excel with no problems.
When I tried to start Word yesterday I got a message saying 'Not enough memory or disc space to run Word' Neither of these should be an issue as I have 8GB memory and over 500gb free on my C drive.
Eventually I decided to uninstall the product and try a re-install.
However the uninstall failed just saying that it was unsuccessful - no error message other than that.

Has anybody got any advice on how I can get Office programs working again

How much space do you have left on your hard drive? To resolve this behavior, rename the global template (Normal.dot). If its pretty full try using TreeSize. Its a free program and works pretty well, it'll tell you see which folders are taking up the most space and then you can go through them and see what you want to remove. Try opening Word in its safe mode, click Start --> Run and paste this line WINWORD.EXE /a if it works ok then it seems to be a non compatible 3rd party add-on, this we can cross if Word works in its safe mode.

I have over 550gb free on my hard drive
I have tried renaming Normal,dot but it made no difference.
Running winword.exe /a gives exactly the same error message about not enough memory or disc space.
The problem now is that after running the Uninstall, which failed, the system is in a very unknown state.
I cannot uninstall, and I cannot re-install
Gerard