Merging Duplicates Error Message

[Anonymous]

I keep receiving this error message when I try to merge duplicates in my database:

owner or user is inactive. Org Id:00D80000000cprP User Id:005C0000003VGxZ

Should I be concerned if most of the duplicates have this error?

Thanks!

[Josh_Hill13]

is your SFDC sync working right now?
Are you using Workspaces?

It may be that the Lead ID was Deleted in SFDC and Marketo hasn't realized this yet.