This is the way I've found to solve this problem.

1) Uninstalled Netbeans IDE 6.5.1,

2) Renamed all subdirectories 6.5 => 6.5.1 that exist under '.netbeans' and
'.netbeans-registration' directories currently under my home directory,

3) Reinstalled Netbeans 6.5.1 than recreating new subdirectories 6.5 under
previously directories,

4) Reinstalled all previously plugin available.

When I've tried to create a new project to do some tests with Icefaces plugin the exception was finally solved.

P.S. sorry for my english.