The verifying assets process stops at 42.2% every time since the last patch. I have Win XP SP3 32bit, fully patched. DirectX 9.0C. It worked fine before the last patch.
Somewhere on the launchpad there is an option to watch the download process - I think under the advanced tools button. You should be able to see the files it's downloading. If it's stopping in the same place %age wise/same file it's more than likely you have a corrupt file. You could try deleting that and see if it helps. Also if the file is an executable, check with task manager and make sure it's not running - EQ2 occaisionally leaves rogue copies of it's .exe file running in background, particularly if it's recently crashed and this will stop the launchpad from updating it. One other thing to check, if you can identify the file it's hanging on, is to make sure it's not set to read only or has some other access/permission resrictions.
