HP SUM + manual install of drivers fail

[Greyhair]

After a recent batch of server upgrades one was failing consistently. the server is DL380G5 running W2K8 SP2 64bit and we have been installing SPaq 8.7
Running the Smart Update Manager many drivers install though some do not. example of the drivers which fail include: iLo mgt ctrl; SA SAS/SATA ctrl; Video ctrl driver; NCU and a couple of others. the error is generic - 'update returned an error - see log.' The log is really helpful - 'The operation was not successful'
Running the driver update excutable individually brings similar results, even in silent mode. When updating the driver manually through Device Manager we are given an 'Access is Denied' error though all access permissions are fine.
Any advice would be appreciated. It worked fine on 4 other servers which are exactly the same model/OS etc.