Could it be my computer?

[Ofnuts]

Gimp works with two sets of files:

• All the files form the Gimp installation. These are shared between users of the same computer
  
• The Gimp profile, which is specific to one user. This where Gimp keeps things for you (brushes, additional scripts, etc...)
  

On the regular Gimp versions, the installation is in C:\Program files\... and the profile is in your user data (C:\Users\yourID...). When you reinstall Gimp, you profile is not deleted, so the new installation re-uses the profile from the previous installation. After reinstalling Gimp you are left with exactly the same file as before, in the installation because you replaced Gimp version N by the same version N, and in your profile because it wasn't changed. If the problem came from your profile (and it usually does), since nothing really changed, the problem is still there and reinstalling Gimp didn't fix anything.

In the "portable" version, everything (Gimp installation and user profile) is kept together. The portable version uses its own user profile and never tries to look for a profile from the regular version. So when you install it, you get a new profile, and if you "reinstall" it, you get a new profile too (oops... where did all by brushes go?). So installing/re-installing a portable version fixes problems that come from the profile.

However, with both regular and portable version, there is a much quicker way to fix problems with the profile. Just locate the directory and rename it. Then restart Gimp. Gimp will create a new profile and everything should work again. Then you can copy the useful bits of your old profile into the new one (brushes, gradients, scripts....).

Windows users are used to fix things by re-installing, because instead of using directory to keep user data, Windows applications store many things in the "registry", which is a database which isn't very easy to backup/restore, and is rarely documented anyway. Re-installing usually rewrites the whole registry data and this fixes things.

TL;DR: if you get a flat tire, do you get a new car?