Hi Sumaiyah,
Thank you for the update.
Place the computer in Clean Boot and then try to uninstall BlueStack and check if the issue persists. Clean Boot will help you disable all third party programs/apps, so that you can complete the uninstallation.
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7/8/8.1:
**http://support.microsoft.com/kb/929135**
Note: After clean boot troubleshooting step, refer to the section "How to reset the computer to start as usual after troubleshooting with clean boot" in the provided link to return your computer to Normal startup mode.