This maybe a corrupt DLL,running sfc should sort this out for you.
You need to run this from an Elevated command prompt.
Open an elevated command prompt. To do this, click Start, click All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator. If you are prompted for an administrator password or for a confirmation, type the password, or click Allow.
Type the following command, and then press ENTER:
The sfc /scannow command scans all protected system files and replaces incorrect versions with correct Microsoft versions.
If Vista is not preinstalled you may need you Vista disc.