Stick a message on the forum at www.macformat.co.uk and/or www.macassist.co.uk ? they're both good forums for Mac stuff.
What type of Mac is it? What's plugged in to it? Will it start up from CD if you insert the CD (or DVD, depending on what OS disk she has) and then hold "C" during the entire start-up process? If you can do the latter, access Disk Utility on the disk and then choose both Repair Disk and Repair Permissions (in the "First Aid" tab). If errors are found and fixed, repeat the tasks until the disk is clear of errors.
As for the whole OS X not hanging thing, it sort of depends which version she had. OS X 10.0 was a heap of shit. OS X 10.1 was bearable. OS X 10.2 was usable. 10.3 and 10.4 have, on the whole, been excellent and very stable. (I only tend to have system crashes when testing unstable alpha software for review, and even that's very, very rare.)
What type of Mac is it? What's plugged in to it? Will it start up from CD if you insert the CD (or DVD, depending on what OS disk she has) and then hold "C" during the entire start-up process? If you can do the latter, access Disk Utility on the disk and then choose both Repair Disk and Repair Permissions (in the "First Aid" tab). If errors are found and fixed, repeat the tasks until the disk is clear of errors.
As for the whole OS X not hanging thing, it sort of depends which version she had. OS X 10.0 was a heap of shit. OS X 10.1 was bearable. OS X 10.2 was usable. 10.3 and 10.4 have, on the whole, been excellent and very stable. (I only tend to have system crashes when testing unstable alpha software for review, and even that's very, very rare.)