Sorry for the blog silence - my Internet was taking a day off today and only recently reappeared.
Having this kind of trouble today in some way neatly fits my troubles of yesterday, where I tried to fix a Windows issue (the updater does not work anymore, and I'm about to give up on it) and ran into the weird effect of the system eating lots and lots of memory in one vile gulp. Well. It took a while to wrench the memory away from its greedy little paws again, and in the process I found a bit of malware lurking, and... oh well. Computer shenanigans.
So... in case you have troubles with space on your system, or want to see what the big files are, or would like to defragment or scan for malware, here's a few helpful tools:
WizTree - a file browser that shows file sizes, very handy to find the eaters of space of doom.
Spybot S&D - scans for malware and adware.
UltraDefrag - defragmentation tool that can even defrag pagefile.sys and hiberfil.sys.