*Shoots computer*

That looks like rundll32.exe, a required system file (or an application which references it) is corrupt.

Try running setup from your Windows XP CD, and it should try to automatically repair the existing installation, and/or download the XP version of rundll32.exe from KaZaA or a friend; Ensure that you're getting the file from someone running the EXACT OS you are (i.e, if you're running a clean install of XP, don't download from someone running SP1a)

Do *not* use Automated System Recovery; If worse comes to worse, just deltree your Windows directory and start from scratch; ASR, tempting though it sounds, will delete all of the partitions on your hard drive and create its own, which means all of the data on your hard drive will be destroyed. ASR is basically a doomsday device and is not reccomended for use unless you have been maintaining regular backups, which is something that pretty much nobody does on their home computers.

Running a reinstall acutally *isn't* a doomsday device, although it may seem like one; XP will detect the existing installation of itself on your hard drive, so even if you do a fresh installation, your desktop settings (ie, wallpaper and such) will remain, and I think that your installed programs will probably all still work without forcing you to reinstall them.

If you go with the downloading rundll32.exe option, remember that you won't be able to copy it over the corrupt version, as it is a protected operating system file; you will have to save it to a floppy, boot into the Recovery Console, and manually copy it to \windows\system32. Make sure that you don't save your updated version of rundll32.exe in a folder on your hard drive, as Recovery Console only has access to a few selected directories, such as your system root, your Windows folder, and (actually, I'm not even sure about this) \windows\system32

EDIT: Before doing anything drastic, though, try going into start -> Programs -> Administrative Tools -> Event Viewer. Select Application in the left-hand pane, right-click, and choose "save log file as..." and save it as a .txt file and attach it.

Sometimes there's something in the Application log that will help.