Loading saved games - Help please

As a newbie i'd like some assistance please with trying to figure out why I get the error message "silent hunter III has stopped working" when trying to load a saved game. I am using windows vista (32 bit) I have the game loaded (not on C drive) patched successfully to v1.4b, loaded GWX, then patched successfully to v1.3.
It is the start of the game for me and there are no problems, my first mission, I am in grid BE32 miles from anyway and I can successfully save my position. I am on the surface with no time compression and no reported or visual contacts. However, although I've saved at least 3 positions in the patrol when I exit the game and attempt to rejoin several hours later the games loads to about 99% then CTD with the above mentioned error.
If I try to load from another point the same thing happens although I have been able to load the game from the start point i.e. in harbour. As I said no problems loading the game or GWX and patch but just loading a save point from the game. I have not added any mods either in port or during the game. Any assistance you can provide or any info you may require further i'd very much appreciate it as it's very fustrating not being able to continue a mission in this exceptional game . I should also mention that i've had lots of problems with ctd's prior to installing GWXX which since it's installation has certainly helped a lot. Many Thanks.