The more common scenarios for this problem are:
1) If the problem does not occur on the Domain Manager DSM Explorer, the most likely cause for it to occur in the remote DSM Explorers is that the remote computers are running DSM Explorers from an earlier version. So, updating them to the proper version level should solve the problem.
2) If the problem also occurs in the Domain Manager DSM Explorer, this means that the internal tables defining the known operating systems do not contain the one reported by these agent computers. In this case, the agent running on these workstations may have been updated to recognize a previously non detected operating system. So, the agent software on these workstations is newer than the one in the rest of the installation.
In this situation a case with CA-Support should be open in order to create a fix to add this recognition also in DSM Explorer.