I have seen this type of effect caused by a few different things. I would
try to boot to Safe Mode and log in that way - it is likely that you will be
able to log in just fine. From there you can try fixing things. The very
first thing to try is the System Restore Point that is most recent, before
the problems started. Even if it does not work, many updates will create a
System Restore Point for you and give you an idea of what might have gone
wrong - even if restoring doesn't fix the problem it can give you a good
place to start troubleshooting in depth.
If you recently added any new software or hardware, that would be the first
place to start - uninstall it. If you have updated any drivers recently, try
rolling those back or uninstalling that piece of hardware. If you don't know
how to roll back a driver, or you try and can't, try unistalling it and
reinstalling the manufacturer's original drivers. I have seen this type of
thing with Video and NIC drivers before, but it probably could happen to
anything.
You can also try checking the event viewer (in the Admin Tools or else
"eventvwr" from the Run box) to look at the warnings/errors mainly in the
System or Application areas. This might show that Hotfix Q###### was
installed just before you started having problems - you could try
uninstalling that from Add/Remove Programs.
You can also try booting to Safe Mode w/ Networking and see if you can
update you antivirus for a full run or use a free online antivirus scanner if
you don't have anything installed. If you don't already have XP SP2
installed, that is definately worth a shot, too.
While in Safe Mode, you can try creating another user to try logging in as,
too, in case your user profile just got messed up somehow. It is always a
good idea to have at least one extra admin account from day one, just in case
you lock out or corrupt your main admin account.
There could also be a problem with a GINA that some program may have
installed - I've seen this type of thing in testing where one program's GINA
points back to itself as a sub GINA, else maybe the GINA is just plain
screwed up. (if you don't know how to work with the Registry, you may want
to skip this, search for how to do it, or ask someone that knows how - if you
make a mistake in the registry there may be no way to recover...) Open the
registry, navigate to and highlight the following key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\Current Version\Winlogon
Look for a string on the right side called "GinaDLL" - if present, look for
another string somewhere in the same area with the same value or another GINA
label (the secondary GINA does not have a defined name - it is whatever the
vendor who inserted the GinaDLL uses - like OldGina or SubGina). You may
also get an idea of who put the vendor there, ctxgina.dll is Citrix,
nwgina.dll is NetWare, I think Cisco has a couple for some of their products
like VPN - these may be some of the more common ones, but there are hundreds
out there - try a search engine to see who the GinaDLL belongs to. Note:
just because there is a GINA there does not mean that is what is wrong - but
if there is a GINA and a sub GINA that both point to the same .dll then write
down and then remove the sub GINA - you may want to contact the GINA vendor
anyways for advice and to report the issue. Their tech support should be
able to walk you through, if needed, deleting or disabling a normal GINA
entry, rebooting to see if that worked, and recreating it afterwards. Also,
make sure the file specified in the GINA is actually present in the location
specified (if there is just a name, it may be in C:\WINDOWS or, more likely,
in C:\WINDOWS\System32)
Hope this helps... good luck!
