...that isn't enough information to provide valid support.
It would help to know if it always freezes at one specific point each time and, if so, which time. Also it would be useful to know what OS you're running (Windows XP, Vista, Ubuntu, etc.), to find known compatibility issues with certain environments, which you could search for on your own. I don't use GIMP a whole lot myself, but I know there can be certain issues that aren't specific to just GIMP itself that are causing your problem.
Did you check that you have the latest version at
gimp.org? You can also search through
the documentation for problems.
The only things I can think of that would cause a problem with GIMP are that the version isn't compatible with your operating system, you have too many fonts (this can take a long time to load, making it appear that the program has frozen up), or a plugin or other GIMP file is corrupt. You might try reinstalling, as well, if you have the correct version already.