You can try below options to see if it helps,
1.Reboot the PC and see if the issue still exists.If so,check if the user has necessary permissions in test lab,if yes and facing the issue have the user try the same on a different workstation to see if she can reproduce the issue.
- If she can reproduce the issue on a different workstation as well,have any other user with same level of permissions try it on the problematic workstation.This was you can analyze if its an userlevel\permission related issue.If its an user level issue,then probably you can remove her from the project and recreate her login,reboot PC and try it.
- If its a specific workstation issue,then probably a clean uninstall\reinstall of QC on the PC and a reboot can help.
