Consider this scenario. In Microsoft Office SharePoint Server 2007, you perform a profile import when domain controllers in a domain are unavailable. The profiles for that domain are marked as "Profiles missing from import". However, each of these profiles belongs to an account.
In this scenario, the MySiteCleanup job does not resolve these accounts from that domain. Additionally, these accounts are deleted together with their MySite sites.
To resolve this issue, apply the following hotfix package:
977023 Description of the Office SharePoint Server 2007 Cumulative Update Server hotfix package (Coreserver-x-none.msp): December 15, 2009
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.