ESXi 5.x Error messages in windows VM for Vmtool service

Problem description/symptoms/errors:
"A timeout (30000 milliseconds) was reached while waiting for a transaction response from the VMTools service"
it is happening with only the windows VMs and it is happening only with the 8.6.5 version of the vmware tools.
http://communities.vmware.com/message/2076676
http://support.microsoft.com/kb/2465772
the above hotfix is only for windows x86 OS.
informed that this error is not an application or service (in this case vmtool) specific but a generic windows error and it can occur with other services too.

What's Happening? :- This issue can happen if your windows are not patched to the latest and if the patching of the VM OS and the VMware tools is being done at the same time.
http://support.microsoft.com/kb/839174

workaround: Perform the windows update and reboot the VM, once the VM is rebooted after the windows patching update/upgrade the VMware tools and then take a reboot. Avoid patching windows and updating VMware tools at the same time and then do a reboot to save a reboot time if you are getting this error.

HP Gen 8 and NMI Driver & HP custom image Confusion!!!

If you have come across a PSOD on your HP servers then you might have been advised to install the hp nmi driver, however now it is not applicable for HP Gen 8 Servers as per HP website but does this mean the hp ESXi 5.x custom image with the nmi driver isn't supported?
Well the ESXi 5.x image with the hp nmi image is supported and during the installation of the hp custom ESXi 5.x the nmi driver will not get installed once the nmi driver detects that it is a Gen 8 server.

For Gen8 servers, system ROM logs the NMI information. On ESXi 5.0 and later, the OS will crash without the HP NMI sourcing driver.

So go on and use the same hp esxi image on all the servers.

Datastores/luns are inaccessible/inactive in Esxi

Issue: - After a power failure some of the luns/datastores are seen as inactive/inaccessible and they are grayed out.
These problematic luns aren't visible in the summary tab of the datastore section of a host but are visible under the datastore view but in a grayed out state.

What worked : Connected directly to the host via vSphere client with the root username and password, tried to add the lun keeping the same signature, right click on the host>rescan for datastores.

What didn't work: rescan all the hosts.
Unpresent the inaccessible luns.
Rescan all the hosts.
Present the luns which were unpresented earlier.
Rescan all the hosts.
Tried the above on 1 lun but no go.
In the vCenter server select the host, configuration>storage>add storage>select the problematic lun>keep the existing signature and proceed but it failed with an error.

vCenter 5.1 unable to login using vsphere client

Issue: When user tries to log into vcenter 5.1 using vsphere client by checking use windows credentials it fails with errors.  It was a mixed environment with 1 vcenter 5.1 & 4.1
"Cannot complete login due to an incorrect username or password"

what didnt work : 

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2035510

1. Log into the vSphere Web Client using the Admin@System-Domain credentials.
2. Click Administration.
3. Under Sign-On and Discovery, click Configuration.
4. Click the Active Directory identity source.
5. Under Actions, click Edit Identity Source.
6. Make note of the information in the identity source.
7. Click Cancel.
8. Under Actions, click Delete Identity Source.
9. Recreate the identity source using the short NETBIOS name in the Domain Alias field.
10. Click Test Connection.
11. Click OK. 

Tried all the above but no go.
 now another error started coming up
VMware Infrastructure Client could not establish a connection with server "<server>".  Details: You do not have permission to login to the server: <server> .
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003872  (please see this link from vmware)

What worked
In the vsphere web client in the inventory service the number of vcenter servers, datastores, hosts and all other entities was 0. Thus it pointed out that the vcenter inventory service has a problem. Restarted the vcenter inventory service.
Issue Resolved. now the no errors when trying to login using vsphere client.

Alternatively
If you are still having the same issue then your might be a known issue where it won't login using the domain accounts but logs you in with the local accounts.
Login with the super username admin@system-domain (5.1) or administrator@vsphere.local and on the vcenter server>manage>permissions>add permissions and add your domain group and give administrator rights to it.