I have been using Maxtor One Touch Mini III to back up to for many months, but now I'm getting an error message "unable to access F:\. Is the network connected or are all removeable devicees plugged".
SyncToy 2.0 should not have such issue. Would you please provide more details about your problem? For example, what OS and what version of SyncToy (1.4 or 2.0?) were you using.
What happens hen you do "dir F:\"? If that works fine ( it lists all the directories correctly) I am not sure what is happening - your only option at that point would be to delete the folder pair and recreate it.