Network share and access problem

Hi I know they may be a repeat post and if so i am sorry. I have been searching for 3 days to fix this problem. there are 3 wireless laptops in my office 2 dells and 1 hp. ok
They all where networked fine for about a year... then:

Dell 1 Can see and access Dell #2 and the HP
Dell #2 Can See and access The Hp; Can See Dell #1 but not access it.
HP can see See Dell #1 and the HP; but only access the HP.

Now i gather the problem is with dell #1 restricting access to both.
I have mapped Drives on Dell#1 and even shared the folder i need to access. But nothing has worked. even made sure simple share was off then back on, even when int the wireless adapters and made sure file and printer sharing was on... PLEASE HELP... ill even post my number for some one to call me i even have an log me in account if you need access.

Hello, I would use the flush DNS tutorial on the Dell 2 and the HP , and see if that helps out : http://www.vistax64.com/tutorials/74209-dns-resolver-cache.html