You must be using the wrong disc mate thats all I can think?
With your save I can get back to 1.00 no problems.
Its easy to check just make sure you have a back up of your save, In a couple of places at least.
Delete game data and delete game saves off the PS3
Install your disc that is the first ever edition of it? It will look like a brand new profile.
You then go to game data click triangle on the information to what version your on. It should say none and a line thru it.
The first update is 608mb which takes you to version 1.05.
I have not deleted anything from your save prior to doing any of the above actions?
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Yeah has its stands if you update it is has follows:
1.01 : 133mb Not sure what happened to these?
1.02 : 133mb Not sure what happened to these?
1.03 : 149mb Not sure what happened to these?
1.05 : 608MB frozen on Home screen (Thats after you click the little house to take you into the GT5 home screen.)
1.06 : 300MB looping starts on Home screen (Not the GT5 screen anymore?)
1.07 : 47MB
1.08 : 1.7MB
1.09 : 49MB
1.10 : 380MB
1.11 : 62MB
1.12 : 13MB
1.13 : 1.1MB
2.00 : 1192MB Am now here updating and doing checks?
2.01 : 112MB
2.02 : 246mb
2.03 : 225mb
2.04 : 79mb
2.05 : 25mb
2.06 : 475mb
2.07 : 2mb