Network wrong username or password

I have a home network of 2 Vista Machines and one Windows 7. All have same administrator user name and password. Recently I have been unable to connect to the Win 7 machine from Vista 1. I am asked for user name and password then get wrong username or password message.All other combinations still work, including Vista 1 from Win 7. I have tried all possible solutions I have found so far on the internet including the different date/time problem. Vista 1 did have the wrong time zone but I fixed this - all clocks now same but still have the problem. Could there still be some residual effect of the time problem?

Try putting the computer name before the user, use the name of the computer you are attaching to. Will look like PCName\username, don't use any leading slashes like you would with a machine name.

Do both computers show the same date including year? You'd be suprised how many people fall over that.

I have another problem which in the wacky world of networking might be significant. Since I fixed the clock error on Vista 1 it (Vista 1) will not stay in sleep. It wakes after about 5 seconds. This happens irrespective of whether other PCs are on off or asleep. I had changed nothing other than correcting the clock when this started. Is there something linking clocks, sleep and time?

Thank u very very much ...i was facing this problem from past 1 month
i would never have any idea that system clock might b a problem in file transferring