Hima,
I had the problem with rubyscript2exe that the link you posted was supposed to solve. I also googled and found a whole bunch of suggestions but none did the trick until many hours passed. I eventually discovered this link:
http://www.ruby-forum.com/topic/170355I encountered the issue when I upgrade my winxp box recently to the latest version of the ruby one click installer. The link above details that there was some kind of security patch which breaks something and you get that "attempt to modify frozen string error".
The solution that worked for me was to uninstall the latest version of one-click and go back to using version ruby186-26.exe which is ruby-1.8.6-p111
I really like rubyscript2exe and was happy to be able to get it working again. I emailed the developer of rubyscript2exe but didn't get any response on this issue either as far as attempting to alert him to maybe providing a possible work around so that people could use the latest version.