http://www.workstationtalk.com/content/sccm-client-not-sending-inventory-information-0
SOLUTION:
1. Run transguid.exe /R on the affected machine and restart the SMS agent host.
2. Wait for few minutes and you should get the hardware inventory populated in SCCM resource explorer.
Note: If multiple machines got affected, you can use PsExec to execute the same command on remote systems. You can download PsExec from http://technet.microsoft.com/en-us/sysinternals/bb897553.aspx
SCCM
