If this error window pops up, clicking in the error window will dismiss it and electrum will run OK. This can happen with Windows 7 or 8.1. If msvcr90.dll is in the electrum directory (or on the user's path) certain versions will cause an error when running the beta. I could find no rime or reason for which versions worked and which ones gave the warning.  I have more than two dozen versions of this .dll on my system and some work and some do not. It does not seem to correlate to the program version number, file size or file modification date.