Please note that this is likely only to be an issue with MacAlly & Acomdata external hard drives, and that a simple firmware update will fix the problem.
Apple has released an update for both server and consumer editions of its Mac OS X operating systems, moving both of them to version 10.3.6. According to Apple's own documentation, the updates include networking optimizations, fixes for video and font glitches, a better-performing Calculator application, bug fixes and security updates.
Users upgrading to Mac OS X 10.3.6 will see improved AFP (Apple File Protocol) service performance, says the technical note from Apple Computer Inc. The update also should resolve an issue in previous versions of the operating systems where SMB/CIFS servers would intermittently disappear upon changes to the network. Other networking changes include fixes for issues in 10.3.5 that appeared when using the Terminal, logging in a user via a network account or trying to open an application from an automounted AFP volume.
News source: eWeek