I have a 4 PC's home network: PC1: P4 2.4, 512MB RAM, 40GBHDD,20GB free). PC2: P4 3.4, 2GB RAM, 300GB HDD, 60GB free) PC3: AMD 3800+, 1GB RAM, 80Gb HDD, 40GB free) PC4: laptop centrino 1.6, 1,5GB RAM, 40GB HDD, 20GB free) All of them use windows XP pro Sp2, with all updates. All have access to the internet & can ping from each other. All use simple file sharing, and share the same group name All of them are virus & spyware free (I assume. I keep monitoring files running on startup & background). All have a few shared folders for others to access them, but when trying to use them, PC1 cannot not even see the other 3 PC's. The other 3 cannot see PC1 either. PC2 can see & access files on PC3 and PC4, but these cannot access PC2 files (PC2 is not accessible). PC3 and PC4 can see & access each other's files without any problem. Now, PC3 & PC4 have a recently clean windows installation. PC1 & PC2 have been used for a while, I have removed stuff, disable services, etc, trying to speed up and increase security. Thanks to this both have been working fine, fast & reliable. Now that I have problems sharing folders, I have disabled Zonealarm, norton, spybot search & destory with the same results. What do you think I might have disabled or how would I be able to fix this problem without having to reinstall windows?