Fixing Error 1324.The path xxx contains an invalid character.

When installing software I have now seen a number of times the following error "Error 1324.The path My Documents contains an invalid character.". My Documents could be replaced by a number of other special folders, and I have seen this issue on Windows XP and Windows Vista.

The problem seems to stem from having UNC paths for folders (i.e. \\server\share\user\my documents). So, to fix the issue you need to temporarily change the path to a local path and change it back after installation. These steps will help (based on Vista, but XP is similar):

1. Click Start
2. Right-click Documents (or Pictures etc.)
3. Choose Properties
4. Make a note of the path currently used
5. Change path to the Default by clicking Restore Default button
6. Click OK
7. If prompted about creating folder say Yes
8. When prompted about moving all your files say no (you are going to move the folder back shortly) and then wait a bit - this might take some time.
9. Install your application
10. Repeat above instructions to move the folder back again, but this time do move the files. This will merge changes to the folder back to your actual folder.