Hi ... The first thing I suggest is to totally remove and reinstall Java (I'm not sure which exact version you have but it could have got corrupted .... and Frostwire. To do this use CCleaner or Revouninstaller or a similar program since Windows seldom does the job properly. It is important to remove preferences etc rather than just the application. .. Make sure first that your Saved files are backed up, preferably to a separate disc.. Just a precaution .. but a wise one to always take.
Then reinstall Java from http://www.java.com/en/download/
using the OFFLINE installer then Frostwire from Downloads above.
To join chat it may help to go to Tools > Options > Community Chat and enter a new name there .... This one should be OK ... then restart Frostwire Note that the Chat and the forums are separate for these purposes.
Let us know if you need more help.