MP3 strange behavior

Hi all
First post, so hello everyone,

I have a basic mp3 player ( ALBA ) 1 gb. The player works well and I've had it nearly 6 years.

But when I connect it to my laptop (running Vista Ultra) via usb and format it there's 996mb of free space.

Lately when adding an audiobook which is, say 185mb long, it will only load two thirds of the audiobook and a small window appears saying can't create no.178 (or stops transfering at 178 when theres 240 parts to the audiobook.

Another strange thing is that I've had "Harry Potter and The Deathly Hallows" (995mbs) on the player and it loaded without a hitch. (May have been magically shortened to get it all on) some how I don't think thats the case.

But why does it accept a large audiobook and then wont even accept just over 100 mbs.

I was thinking that the formatting application on Vista is at fault.

Any ideas on this one please.