In Vista when you run CCleaner, it deletes the C:\Users\Username\AppData\Local\Temp\Low folder. This causes Internet Explorer 7 to give you an error message when attempting to print. I have found a work around which must be done every time you are done running CCleaner. First you have to go to C:\Users\Username\AppData\Local\Temp\ and recreate the Low folder. Then you have to run the following command: icacls C:\Users\Username\AppData\Local\Temp\Low /setintegritylevel (OI)(CI)low I responded to another post about this, but it wasn't in the bug reporting thread, so I thought I would add it.
I have read that this error only occurs if you have moved your Favorites folder from it's default location. Did you ever move your favorites? I have and I had the same problem after running CCleaner. I also would like to be able to run CCleaner without having to recreate the low directory and run the icacls command everytime. Hopefully they release a version soon that doesn't delete the low directory. I thought I had finally found a cleaner program that didn't cause problems until I tried to print in Internet Explorer 7. Every other cleaner has messed up at least one thing. This seems to be the only thing that CCleaner messes up, so I'm hoping not to discover anything else.