vSphere 4.1 Client "Cannot complete login due to an incorrect user name or password" with new AD accounts

I've got a VMWare ESXi 4.1 server connected to a vCenter server, with an active directory domain. This has been in place for at least a couple of years, perhaps more. Using the vSphere client 4.1, when connecting to the the ESXi host I receive an error "Cannot complete login due to an incorrect user name or password".

User name is specified as: DOMAIN\User Name (with a space in the username)

This same use case is functioning correctly on a second ESXi 4.1 server we've got running. Both ESXi hosts were built and installed/configured at the same time with identical versions and settings, and are on the same physical switch. The domain controller is hosted on the "other" ESXi host which i am able to successfully log into.

vsphere error message screenshot

The credentials are the ones I use to log in elsewhere in the domain, so clearly they are correct. I even make sure to match case with AD after reading that this sometimes is the problem.

My user account is only about 6 months old. Another user, who has been using the system for much longer, is able to log in, but any new users are not able to(i.e. a copy of the functioning account). Currently I should be entitled to log in by way of group membership, but just for kicks he tried to add me explicitly from the vSphere client after he logged in. He was able to find my user object, when he searches for available users, but it gives him an error about not being able to find the user object when he tries to actually add my user object explicitly to the ACL.

Further research shows that there might be a SID conflict which is causing this, according to this VMWare forum post

A lot of reading I've done has said that in ESXi 5.0 and 5.1, this problem is caused by authentication problems with the vsxuser account, but I can't find anyone who is experiencing the same issue in 4.1.

So, enough background. The questions I need to know are:

1. would recreating the vsxuser on the nonfunctioning host solve the issue?
2. If so, what are the correct steps for doing this on ESXi 4.1?