Error opening pidfile

My firefly setup on an NSLU has been running great until recently. I updated to the most recent nightly (1586) as I have a second Roku Soundbridge which is an M1001 and all worked a treat however I am now getting an issue with Firefly starting on the NSLU with the error “Error opening pidfile” which causes mt-daapd to abort instantly.

Log:
2007-06-10 00:21:33 (00000400): Firefly Version svn-1586: Starting with debuglevel 2
2007-06-10 00:21:33 (00000400): Plugin loaded: ssc-script/svn-1586
2007-06-10 00:21:33 (00000400): Plugin loaded: daap/svn-1586
2007-06-10 00:21:33 (00000400): Plugin loaded: rsp/svn-1586
2007-06-10 00:21:33 (00000400): Starting rendezvous daemon
2007-06-10 00:21:33 (00000400): Starting signal handler
2007-06-10 00:21:33 (00000400): Error opening pidfile (/var/run/mt-daapd.pid): Input/output error
2007-06-10 00:21:33 (00000400): Rendezvous socket closed (daap server crashed?) Aborting.
2007-06-10 00:21:33: Aborting

If I navigate to the file in question I get an error:

“./mt-daapd.pid: Input/output error”

If I try and delete the file (to reinstall) I get:

“unable to stat ‘mt-daapd.pid’: Input/output error”

I am assuming that this file has somehow got messed up but don’t know enough about what I’m doing or seeing to know where to go from here.

Has always run sweetly until recently so I can only guess something has gone horribly wrong.

Any suggestions or help wuld be hugely appreciated. 😳