Tsjerk

I don't see where in the code this would be happening. Can you try the latest version (1.2.0) and if it doesn't work send me the input and output?

In an XTC file, the header contains the size of the coordinate section in bytes, and the header itself has a fixed size and starts with the magic number 1993....

Oh, reading through the original issue: 1. Finding the last frame is done by reading the first and saving the header tag (8 bytes: magic number and number of atoms),...