Windows 7 refuses ANY network filesharing!

guys im stumped, and frustrated

Working on the presentation that determines if i graduate with a bachelors in electrical engineering or not, and windows has failed me yet again.

All i want to do, is share a folder, a drive, ANYTHING. It wont. it used to, but suddenly, it wont. Nothings changed. Windows firewall is off. Ive done the most unsecure idea and left a drive shared to "everyone" with full permissions. Nada. Cant connect from the mac i'm using, from any other windows PC..it just says "Cannot access share"

Everyones on the same homegroup. Said finiky PC refuses to connect to anything else also. This problem just sort of started getting worse out of nowhere. First i couldnt login over the network, had to login as "guest"..it would show me a few folders/drives but only allow me to access the public ones. Now, nothing.

Im doing renderings/CAD drawings on the windows PC and incorporating them into a powerpoint on the mac. Its adding TONS of time to keep transferring to a USB drive.

I have half a mind to see if solidworks can run on WINE rather than try and fix windows. Again. Any ideas guys?

Thanks in advance.

Can you give it your Windows username and password when trying to access it remotely? You may have to do computername\username as the username.

Checked the system's event log to see if there are any useful error messages.

If it did work before and now it doesn't, something as definitely changed. Has Windows Update applied any hotfixes or patches automatically? Is file sharing turned on for your network? Can you see your own shares in the start > network? And if that's yes, can you see the shares from other computers from start > network? Have you tried manually typing in \\hostname, or even \\192.168.x.x (insert correct IP here)? MIght seem odd but is the time synced on all the computers (this includes timezones as well)?

On your Windows 7 machine, try leaving the workgroup. It was the only way I could get my machine to recognize some XP rigs I have on my home network.

Also, if the system time is off on your Windows XP or older, and is different from system time on Windows 7/8, then Windows 7/8 will have trouble accessing it.