Cannot start NIS

Oops!
ERROR 305
NEM Infrastructure Server is not available.
have you started nis by right clicking nem monitor and hit start nis?
Yes, but is not starting
Java up-to-date ?
Where you running an older version of the client before ?
Any very old wallets still there ?
OS ?
standalone or webstart ?
Installed the NEM webstart two days ago, and was working perfectly! No changes and today NIS is not starting! OS is Windows 7
That's very strange.
Any chance NIS is already running in the background ?
How many java processes do you see ?