Might be old news - apologies if it is - but Canon Australia are now linking to new firmware V1.36 for the IPF5100.
Not sure what the fixes/advantages are - they don't say. But I have succesfully installed on my IPF5100 without issue. Make sure you install the firmware update tool first however.
I haven't noticed any differences - other than it does seem to start printing ever-so-slightly quicker when sending files to the printer.
X-posted to the Canon IPF Wiki.
Happy printing all.
