Rollin' Rog, I will try that in a bit - just wanted to post this first, as I feel sure that it's something to do with the permissions/security settings for the program files folder.
Here's some screenshots of the settings for program files at the moment:
The "Admin" account is the adminstrator account I am trying to install from. Do you see any irregularities in these settings? Is the owner also correct, should program files be owned by adminstrators or a single user account?
I have noticed that the folders that existed before these problems (for example the Microsoft Office folder, which is obviously installed in program files), are owned by Administrators, whereas the new folders that are being created when I try and install programs now, are becoming owned by "Admin" - I don't think this is correct is it?
I also just tried creating a new temporary folder on the root of the drive, and tried installing to there instead - this worked fine, if the worst came to worst, could I just create a new program files folder and transfer everything over?
I really think the key to this though is the owner and permissions settings - opinions? Thanks