small horizontal squiggle? does it look like "~" its called tidle i think and is shift + hash(#) key.
you normally get the tidle pointing to a long file name over so many characters like documents and settings
.dll files are normally just "example.dll" for instance.what is the dll file called?
you could try if its xp clicking start/run and typing "sfc /scannow" (space after sfc and before /) if 98/me/etc i think its just "sfc"
insert your windows disc when prompted to restore missing dll or system files.
hard disks are never the capacity advertised as there are 1024kb in a MB but most manufacturers use 1000= 1x MB for some strange reason i think.in that case 120GB advertised is actually only 117.1875 gigs.my maths are not very good so i may be wrong but your does seem a lot less??