Nobody else experiencing this issue? I must be really unlucky!
Since posting the above, I decided to try a complete uninstall of both LR 4.4 (was meaning to remove this anyway) and LR 5. Did this yesterday and managed to shutdown/backup/optimise the catalogue without issue. Today, I shut it down and Windows logged an error code, right at the moment before it completed the backup process (the final stage being optimisation).
Really puzzled by this. No such error codes were getting logged until I upgraded to LR5.
You are not the only one. The "stopped working" message I have sometimes when quiting LR5. This message also appeared sometimes when opening earlier versions of LR4. It does not bother me anymore. It could be a lightroom but also a windows problem. I hope it will be fixed somewhere in the future .
Found this in the application logs: (20130702)
Faulting application name: lightroom.exe, version: 18.104.22.168, time stamp: 0x51a64dae
Faulting module name: gdiplus.dll, version: 6.1.7601.17825, time stamp: 0x4f9242bf
Exception code: 0xc0000005
Fault offset: 0x000000000003c579
Faulting process id: 0xf94
Faulting application start time: 0x01ce775990789dfe
Faulting application path: C:\Program Files\Adobe\Adobe Photoshop Lightroom 5\lightroom.exe
Faulting module path: C:\Windows\WinSxS\amd64_microsoft.windows.gdiplus_6595b64144ccf1df_1.1.7601.17825_none_2b 253c8271ec7765\gdiplus.dll
Report Id: 807ccbf6-e34f-11e2-b38b-bcaec59296ab
Thanks for letting me know I'm not alone with this! The log you've included in your post is exactly what I've been seeing.
So far as I can establish, the gdiplus.dll is related to graphics rendering/user interfaces. If there were any actual rendering issues whilst using LR then I'm quite sure I'd notice, and would also expect errors to occur/be logged whilst using LR, not when closing it down. It doesn't seem to actually be affecting any of the backup or optimising processes... Odd.