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Serialization Error

I have a program I have ran several times and ran fine. Today I try to open it
and I get a "Serialization Error" "Error: ALT". Is there a way to correct this or is the program junk now. I try to open it with 3.5 MR2 and 3.7 MR3 and I get the
same error message. I was running it in 3.5 MR2. Thanks for the help.