Sorry to necro-thread, but anyone finding this in future should be aware that system TIME is CRITICAL in Kerberos applications, e.g. Active Directory. I believe workgroup shares (e.g. non-AD) have time issues as well, even though Kerberos is not involved there.
If the delta of system time on the different machines is out of sync more than 5 minutes, you are asking for trouble. 10+ minutes out of sync and it is pretty much a given you will have major issues, especially in an Active Directory domain, including PDC/BDC/DC's not synchronizing, logins not working, shares inaccessible, etc. If you are experiencing this issue, check that the time is synchronized on both the machines that access and serve the shares.
This time sync issue especially tends to crop up on virtual machines due to the way the internal clocks are virtualized. This has gotten better over the years, but still tends to rear its ugly head from time to time (no pun intended).
In an enterprise/small business, use a common external NTP source for all machines if at all possible, this insures time synchronization. Even better is to run a single (or multiple) internal NTP time source machine(s) for your company that connects to the NTP network for its time. If your systemcannot reach the internet because of a DMZ or some such, or are not permitted to do so by company policy (the firewall ports are not open), run an internal NTP server on a bare-metal system that is checked for accurate time frequently. The US Naval Observatory master clock (atomic clock) automated voice announcer still works, at (202) 762-1401. I used to do this with a remote system for years in the late '90s, and it worked great as long as I checked at least once a week. Sometimes ancient tech is the best tech.