Tortoise SVN - nothing happens when clicking content menu commands

I have Tortoise SVN 1.6.15 installed on a Windows 7 64 bit machine. It was working fine until yesterday. There are the two problems that I see:

1. When I right开发者_如何学编程-click to open the context menu and click on SVN command (Checkout, Repo-browser, etc), nothing happens. No error message, no spinning-icon, nothing. As if I didn't click anything.

2. When I click START > ALL PROGRAMS > TORTOISE SVN > TortoiseSVN, I get a popup error message The ordinal 728 could not be located in the dynamic link library mfc90u.dll.

The only change to my system that I did yesterday was to install Slik Subversion 1.6 in order to get the necessary 64 bit files to get Subclipse working on a 64 install of Eclipse. I have since uninstalled Silk Subversion, but I am still getting the same error.

Thanks to anyone with ideas to help me.