Two points.
1- I never use a memory module in any PLCs, and I have never said "Gee, I wish I had a memory module". This is a good option for an OEM to use with customers who cannot support PLC programming. Since you can presumably backup and modify the program, I would just disable the 'load from memory module on power up option' (paraphrased). That way, the contents of the memory module will not be downloaded to the PLC on powerup. I believe you can make that change in the processor properties. I do not have my Logix 500 software available right now, so I would have to figure out a work-around for write protect, or whatever else is going on. If you wish to keep the memory module, I'm sure the answer will appear here eventually.
2- We are actively replacing our SLC processors as they are functionally obsolete. CompactLogix controllers are really not so expensive anymore, and there's a migration utility to change your program from the SLC to Logix format. Also, a CompactLogix PLC will support Ethernet connectability, rather than the serial or DH+ protocols you are limited to with the SLC. This might not be the best option if you are communicating to other devices over DH+, RIO or other.

Brad Waybright

It's all okay as long as it's okay.

Excellent points.

Keith Cress
kcress - http://www.flaminsystems.com

I have seen this error before on a old machine, It prompted a project to up date the controls system on it. Temporary I ended up trouble shooting to find that the EEPROM was bad it self. I was able to find another one and it worked.
There may be a work around for this maybe a external unit but I did not research it any more, the controls system was up updated a few months later.