[quote=Khaled]This appears to be a Windows editbox limit - it has a maximum single line length limit of 4096 characters./quote]
Under vista-64, i reproduced this error a lot shorter than that. Unless mIRC has a lot of hidden data attached to each line.
//set %tempvar $str(a,3062)
doesn't produce the error, but this does:
//set %tempvar $str(a,3063)