Probably, this is more complicated than a simple preference corruption, but you may rule that out in the following way:
To restore the preferences, you may either Ctrl/Cmd+Alt/Option at startup, or Move the folder with Illy closed. The latter is recommended here because it is reversible and takes care or more issues, but requires a greater effort, especially the first time used. See explanations in the latter.
If you have Vista, remember to reboot before waking the beauty from her sleep. Reinstalling does not replace the preferences.
When it is not something in the Adobe Illustrator CS3 Settings folder, it may be (with tests):
1. Corrupt font(s): you may move all fonts out of the Windows fonts folder (and move them back in);
2. Firewall interference (especially if more than one is running (XP SP2 adds one if activated)): you may turn them off (and on again);
3. Some versions of Acrobat generate many temp files. Too many (64K) causes the problem: you may search and destroy Temp files;
4. Some other inconsistency caused by Adobe Acrobat/Reader: you may try uninstalling and reinstalling (a newer version).
5. Incompatible/old printer definition file for the default printer: you may upgrade the driver, change the default, or set the PostScript driver/PDF to default;
6. Using a US/English version of Illustrator with Windows set to a different language: you may enter Control Panel>Regional and Language Setteings and change to English (and change back).
7. Quicktime/iTunes: uninstall Quicktime and make sure the Quicktime folder is deleted in the Program Files folder; and/or uninstall iTunes.
If none of these possible solutions work, have you made any (other) changes to the PC between succes and failure? New software loaded?
Please be more specific. What operating system? How was it installed? In any case, try to trash the prefs as per the FAQ as a first step.