You can try restoring the OLEACC.dll by running System File Checker.
I don't use Vista. I'm a Linux user but it should be the same as XP.
Open Run and in the box type in SFC

If it says you don't have the proper privileges close the Run box, highlight the Run command, right click on it and run it with elevated privileges.

Let SFC scan your system for missing files. If it finds that missing dll you can tell it to replace it.

Good luck!