[QUOTE="Brownz"] Price is still the factor, compare the price of a 40GB HDD to 40GB worth of DRAM modules. [URL]http://www.dramexchange.com/[/URL] I think the small factor drives (1" & 1.8") are pretty damn robust in general - knocks and drops etc When you attach them to a semi flexible mount in a vehicle that has constant vibration and occaisional multi directional shock, then its a data disaster waiting to happen. Thats why people like Hitachi design drives (Endurastar) for automotive purposes. Being 2.5" though I guess they tend to be ousted by the likes of Tom Tom in favour of smaller drives so they have a more compact end product.[/QUOTE] I MIGHT have fixed it. When I looked at the files on the TT via the laptop, one of them was corrupt. It has two map folders - Western Europe and The Canary Islands (FFS). The Canary Islands folder was unreadable and couldn't even be deleted. I copied everything BUT the Canaries to a laptop temp folder, formatted the TT, then copied the files back. Bingo - a working Tomtom again. I guess I won't be able to navigate around the Canaries this summer, but that won't be too much of a hardship. Looks like a single corrupt file was holding up the whole operation. Off to France in the morning, so we'll see how long it lasts. Thanks to all for the enlightening observations and advice.