I've recently had a problem with ALL of my Android devices not seeing my Win 7 shares after upgrading my home server from XP (on XP they all managed to see them fine using ES File on the devices, for years) - all clean installs and shares all defo setup correctly but no matter what i did all the android devices would either keep asking for a password or just keep spinning. After a few attempts at rebuilds using both 32/64bit versions of Win 7 and alternative android apps with varying success I tried a fresh install with NO MS updates installed - magically everything worked fine. Installed my BitDefender suite - still all OK for days. Then ran the MS updates until they were all done (200+ over a day or so) - shares all went dead again. So.... i was now pretty confident that in my case it was an MS update that stops it working on my machine.
I do have another win 7 machine though which is all MS patched up and it doesn't have the same issue and the shares on that all work fine.
I decided to try one last thing and installed and old 3com network card and bingo - all the shares started working again.... Server now all patched up and running like it was before with me able to brows the shares, stream etc. etc. with no issues at all - 5 days and counting.
For me it seemed that an updated network card driver was the most likely cause of my issues but it took weeks to find that out as the shares all worked fine with all my other win 7 machine attaching to the shares, it was just the androids that didn't work. My original nic was an onboard type.
So maybe worth grabbing a cheap nic card and installing it in your PC if you're having similar issues, or a cheap wifi dongle or something just to get the connection away from your current nic. Certainly worked for me.