Click on "Start" and select "Control Panel".
Find "Java" and double-click the icon.
Under the "General" tab choose "Settings".
Make sure that the checkbox at the top is CHECKED and choose "Delete Files".
Make sure both the "trace/log" and "cached applications" checkboxes are checked and choose "OK".
Now, close the other windows by choosing OK and
try to enter/open your Collaborate session again.
Note: It will take a little while longer to download and start Collaborate for the first time after doing this.
If you need to know how clear your Java Cache on a Mac computer, then please visit the JAVA/MAC instructions.