Error saving game in Fallout 1

I recently adquired Fallout 1 along with patches 1.2, 1.3 and the High Resolution patch. I installled, patched and started to play but after 4 days I got an error.
I was searching The Glow last night (an area of the game) and I decided to save game and go to bed, but I got and error instead. Something like "Error saving game! Unable to save game". Also I was saving over an old save file, and the game deleted the old save after the error.
Does anyone know what could happened? I have advanced a lot in the game story, and I really don't feel like starting all over again.
BTW these are my PC spec's: Windows 7 32 bit, the game is installed in D and I perfomed the humungous installation. Thanks in advance.
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