Wow some of that stuff is complete overkill. I bet it had something to do with the classic vs. guest type of file sharing, which seems that resource kit they recommend fixes for you.
I tried to find the option, but I have Vista and they have completely redid the UI for sharing so I can't tell you what it looks like in XP. But yeah there was an option in one of the MMC snap-ins to use classic sharing (accounts and passwords on the networked computers must match) and guest sharing (basically anyone can access the share in the network).
But I've always had trouble with the guest sharing.
Also keep in mind there are share permissions and NTFS permissions and they both apply on a file share (if you are using guest sharing, it uses the Guest account's permissions, and the Guest user is disabled by default).
Edit: Yup. Here is the likely fix:
FOUND IT!
Ok, same problem as everyone else.....
2 computers, one laptop, both XP Pro
Dell to laptop, can't access
Laptop to Dell, no problem
I do not want to download scripts from MS from 2003...
SOLUTION:
Start/Control Panel/Administrative tools/Local Security Policy
1. Security options/Network access: CHANGE to classic, users logon as themselves
2. User Rights Assignment: Access this computer from the netowork: add (by typing) "Administrators"
This works if the user (me!) is admin on both machines. Haven't fully tried if it works yet, but sure do get access both ways for the first time since I started trying, yihaaa.
I've spent hours and hours trying to fix this, reading all forums on the net....
Good luck, hope it works for you.
I was able to find it in Vista in the same place. I'm not so sure step 2 there is completely necessary. I've never had to mess with it in the past.