I am using Ubuntu 11.04, with unity. It's an "inside windows" installation using Wubi, and I've installed on an external USB-HDD.
More and more now, my computer does not shut down properly. It gets stuck on a final black screen, where I can do nothing but do a hard shutdown (press and hold power switch). This is rather painful, as I do recall someone saying that Linux is more sensitive to that than Windows.
Before, it has always worked anyway, no harm, no foul, but today when I booted up, the graphics are different (worse), and I am in Gnome, not Unity. (weird!) I never used Gnome, so I am assuming it is falling back on some default safe-mode.
I've tried the grub startup option labelled "(recovery mode)" before, and that seems to do something, but it does not seem to have fixed the problem. Sometimes, it seems as though it is the uptime that is the culprit, the longer, the worse it is.
Also, but it may be unrelated, from the very first time I installed Ubuntu, I've had some problems with the boot. It goes through windows bootloader, then says something like "error: prefix not found", goes to grub, where it says "error: file not found // error: you need to load the kernel first". Pressing Enter again too fast gives another error, but if you give it 1-2 seconds, then press, Ubuntu boots as normal. I have assumed it is because this external HDD is external, perhaps it is slower, needs a nudge, etc. But it may be related to the problem, who knows.
Specs as requested in comment. Running Windows XP/Ubuntu 11.04 on a laptop (3-4 years old):
INTEL CORE2DUO T9300 2.5GHZ 800/6M BOX 2 x Kingston 2GB 667MHZ DDR2 NON-ECC CL5 SODIMM CHIPSET Intel GM965 PROCESSOR Intel® Core 2 GRAPHICS CARD NVIDIA GeForce Go 8600M GT GRAPHICS CARD MEMORY (MAX) 512 MB