SPS2003 cannot access default root site, but can access sub sites...

I have a sps2003 on w2k3, and after a bad install of another vendor's software, it broke my portal on the default website. I finally got it working, but only for a day. It had been givng 404 and 403 errors, until I changed the app pool identity to one that had access to sharepoint. Then without warning, the next day I can no longer get to the default root page. I can type in the url of a sublevel site, and get in no problem. But if I try to traverse back up to the root site, I get unauthorized access error, from within Sharepoint

Now I have a feeling that SPS is crippled, and I have tried running a repair, and updating the sp, but it hasn't worked. Short of uninstalling/reinstalling, is there anything else I can do

I am a newb when it comes to SPS, so go easy on me. I inherited this mess, and am trying to get it straightened out...

Yes, exactly. The new software did install to the default site root, which is a managed sharepoint path. Is there anything I can do to fix this

I have removed it, obviously. But nothing I have tried has brought back the root site. I'm trying to avoid uninstalling SPS, and having to reinstall it.

I cannot get to this, as it give the same error as the default root site. "You cannot view this area, either because it no longer exists, or because you do not have the rights to view this area. To change your rights, contact the site administrator."

Which of course I am, and the site content/pages are all there.....

Would saving the db's, and content, then removing/reinstalling SPS2003 resolve the issue What about any insight to which db stores the access rights, and what value would I need to look for