Help please - Robofil 310 E503 error code - Illegal filename

Hi, I don't know if anyone has encountered this problem before.

We have recently encountered a new problem with our Robofil 310.

We import machining programmes using 3rd party software via an RS232 link. This has been very reliable until the last two days.

When we select the following on our EDM
F5 - Files
F1 - Copy
F7 - PR

And then type in our filename e.g. CD1219 we get the error message ON MEM E503 ILLEGAL FILENAME

As far as we can see the filename CD1219.ISO meets the requirements so we are a little baffled as to why we are getting the message.

We have re-initialised the software and deleted some files to ensure the memory is not full but this has not solved the problem.

Any help would be greatly appreciated.