Here, a very easy to follow going back to Gingerbread stock, follow carefully:
You can download any official firmware at http://fus.nanzen.se/
1a. Download Fus Check Downloader 2.1 from the above site. Using the Fus Check downloader, download a Firmware for your region. It will automatically decode the .enc2 file to.zip file
(For your case choose GT-P1000M)
1b. Download Odin3-v1.85
2. Extract the .zip file generated from decoding file to a folder and you will get
tar.md 5 file.
3. Start Odin - put the .md5 to PDA
3a. If your last firmware was gingerbread, leave everything else as is (No .pit file, leave repartition unchecked).
3b. If your last firmware was NOT gingerbread (get pitfile, and check the repartition) Note -- open up the.md5 package to check if there is a pitfile included,
as well as dbdata included. If they are included, you don't need to find pit file again, you can use it for your flash.
4. Go to download mode on the G-tab, connect it to your computer,
and click start on Odin. It takes about 6 to 7 minutes to do the flashing.