There is a problem with parsing FASTQ data *if* verbose comments appear after the '+' character. To be precise, the current version of MAQ examines this line up until the first whitespace character to ensure it matches with the comments on the first line (starting with '@'). If anything appears after the first whitespace, it will be treated as quality scores and the parsing will become out of sync after that. This was reported by aihardin as bug 2121067.
The attached patch for seq.c simply adds a loop to grab the characters between the first whitespace after '+' until the newline character. This loop was already used earlier for the first comment line.
(Obviously, if there is nothing between the first whitespace and the newline on the '+' line, then this patch is not needed.)
Fix for incorrect parsing of FASTQ data