I finally figured out that Java 7 was causing the problems on my computer. I got it working, so I decided to post my solution here. I was receiving this error after login:
"You are no longer connected to the Symantec Endpoint Protection Manager. You must log on again to continue."
... followed by:
"Unexpected server error. [0x10010000]."
I was able to work around it by editing the shortcut, which was pointing to javaws.exe in my Windows directory. I explicitly set it to point to my 32-bit JRE 6 location instead, since I had Java 6 and Java 7 both installed. If your JRE is in a non-standard path, adjust as needed.
Make sure you have the 32-bit Java SE Runtime Environment 6 installed (latest version recommended). If you don't have it, you can get the latest from java.sun.com in their archives. http://www.oracle.com/technetwork/java/javase/downloads/index.html
For a 64-bit OS, change your JRE to the following:
"C:\Program Files (x86)\Java\jre6\bin\javaws.exe" -localfile ... (the rest of the shortcut)
For a 32-bit OS, change your JRE to the following:
"C:\Program Files\Java\jre6\bin\javaws.exe" -localfile ... (the rest of the shortcut)
Please note that the "C:\Program Files\" path doesn't work on a 64-bit machine, even if the file exists. It will hang after logon (or alt least mine did).
I can vouch that this worked on Windows 7, 64-bit with JRE version 1.6.0_32 (6 update 32).