Hi Dave, It appears that the old user account is corrupted due to which you are facing this issue. I will recommend you to transfer your data to the new user account and use the new user account from now on. Please reply in case you have any further questions.
After running the Windows 7 System File Checker (Laptop Inspiron 1545), and rebooted, it has disabled the following software which cannot be reinstalled: 1) Dell Dock - Downloaded DellDock16a_setup_ENG.exe, after installation a): error message 'Dell Dock has stopped working', after reboot, Dell Dock is not visible. 2) Dell Wireless WLAN Card - Downloaded R206848.exe ('WLAN 1510 Half card', detected from the Service Tag), after installation a): error message 'The operating system is not supported. The software will not be installed. Setup will now exit.' Update: The following device is visible under Network Adapters: 'Dell Wireless 1397 WLAN Mini-card', and says 'This device is working properly' in Properties. Any suggestions to allow a successful reinstallation would be much appreciated. Dave. P.S. SFC also disabled JustCloud backup, which also cannot be re-installed (under investigation by JustCloud).
Win 7 System File Checker - Disables Dell Dock/WLAN Card