yep, I have the same issues with my SA repos. since the update to 4.5 the replication is not working. also tried new systems to act as SA repo, but same issues. Switched to UNC repos now... :-(
Do any policies enforce on these machines? I would toggle the "Show agent tray icon." setting on the agent the wake up the agent and see if that enforces. This may be a comm issue or a policy enforcement issue.
This is referenced in KB67453 "ERROR: Access Denied (SuperAgent Repository replication fails after upgrading to McAfee Agent 4.5)":
I'm kinda curious because I use superagents and I've upgraded all my agents to 4.5 yet I'm not experiencing this issue in my ePO 4.5 environment...