First of all you should have only installed 2.7.1 after you rename your 2.6 version to anything other than 2.0 in your program files list. because the new installer for 2.7 uninstalls ALL versions of 2.0 no matter where you install 2.7
Keep that in mind for later.
If 2.6.10 was uninstalled ...reinstall it, and before you dl 2.7 again...rename the 2.0 folder to something else, rename it back again after you install 2.7.
Also keep in mind when you install 2.7 and if you have 2.6 installed already, Gimp will COPY your user docs 2.6 folder for 2.7, and rename that copy "gimp 2.7" ....that means everything in 2.6 user docs folder will be used for 2.7 and renamed user/2.7....so every script,brush,and whatever else in there needs to be deleted in the new 2.7 folders because most of it isn't compatible with 2.7...understand?
This is why you should create a 2.7 folder before you install it...especially if you have 2.6 installed already.
Then Gimp will see the 2.7 folder you created, and create sub folders that are empty inside it.
That should work.You will then have 2.6.10 and 2.7 installed.2.7 is a test version, so a dos window will pop up every time you use it, you can not close this window, just minimize it.it is for de bugging.It must stay open for 2.7 to run.
Let me know if that copy i uploaded works for you.