Sorry I couldn't be of more help.
The current version is 2.19.003, and is working fine. So if you are elligible for update, I would suggest that.
Other possible redundant methods if you can't upgrade:
1) "File>Open Suite"
2) Go to the Theme Manager directory and right-click on a .suite file in the "themes" folder and select "Apply theme".
3) The oldy but goody: Uninstall, Reboot, Reinstall.
Here is a list of the .dll and .ini files shown in my working Theme Manager (2.19.003) directory:
applications.ini, display.dll, inetconfig.dll, mssprv.dll, skin.dll
I would verify that these exist in the directory.
Other than a corrupt install, user account limitations, or a limiting setting somewhere in the system - I am at a loss.
I'm sure that someone more advanced than myself can be found to help.
Good luck.