GNUplot execution failed, on some graphs

[BooX]

Hi

I'm using a CF-card and a cardreader on my NSLU2 and it normally works perfect.

After trying to replace the reader with another one and swapping back to the original reader ( shutdown done properly every time ), some of my graphs won't execute. And the strange thing is that if take a graph showing 24 hour data it fails, the same graph for 1 week works perfect ???.
I haven't made any changes to the graphs for the last 2 years, they just stopped working after the test of another reader.

I have looked briefly through the data and didn't find any corrupted data, but I'm not 100% sure there isn't any.

What would be the next thing I should try to safe my old data and have a working system ?

Thank you in advance.

BooX