hi! my english is not good. but please help me.it is very important for me. i have a lan with 20 computer.and a sever .i had not any problem but now it is terrible for me. when this problam began one of my computers do not login (login in domain)and other computers do the same.and this computers do not see (connect) other computers in my lan.and my server can not access them . I checked the cables (rj45) .and hub.and i reset my active directory.but i have this problam. of course few minutes these computers work true but it is for five minute for example!! i can say some details about my lan if you can help me. i do nat forget your help! thank you.

when the workstations can't logon to the server can they ping? example: ping [server name or ip address] If they can not ping I would suspect the hub/switch connecting the 20 wkstations to the server. See if you can ping workstation to workstation. If you can then look at the servers network interface card [nic]. Replace faulty parts like the nic or the hub/switch. Post back if you can ping the server when you can't logon and you can ping from workstation to wkstation.

HI! Thanks for your help. I pinged from all stations , but my problam it is that sometimes they ping and sometimes don't ping! for example now one of them don't ping but after 3min ping,again don't ping and.... You had say that may be my hub connectors (rj)have problam.but why all of them ! or may be my hub have problam? but 2 computer have not any problam. When the computers do not ping log in after 1 hour!!! but when ping , login in 1 second! What can i do? i will be crazi soon! and again thank you!

replace the hub with a new switch. If only two ports out of twenty work after 5 minutes it means the hub is bad.

definately replace the hub with a switch. Dlink makes a hgood 30 port switch for a low price. I have used one of them for two years with no problems.