ADOR.RecordSet and Vista

I've inherited two sets of VB6 based com components from another developer.
A set of client side activeX controls and a set of server side com controls.
Basically, browser activated client side activex controls invokes server side
control on Windows 2003 server as

Set objUser = OpenObject("SBOUserInfo.CUserInfo", strServer)
lngResult = objUser.ValidateUserInfo(strUserName, _
strPassword, _
mrsUser, _
mrsSubCompanyAccess, _
mrsWorkGroups, _
mrsADOError, _
mintPWDUserStatus, _
mintPWDDaysToExpired)

where all of these mrs... objects are ADOR.RecordSet objects
like Private mrsUser As ADOR.Recordset , etc..
Eventually passing ADOR.Recordset across the wire.
The application is working just fine in all Windows versions, but Vista.
ComChecker shows 2.81SP1 ADO version on client XP machines, "unknown" - on
Vista, which comes with it's own set of ADO dlls.
On Vista the client side ValidateUserInfo call to Windows 2003 server
machine produces -2147024809 error. - One or more agruments are invalid.
So, client-server calls like "any windows,but vista"-"any windows, but
vista" work fine, "vista"-"vista" calls work fine, but "vista"-"any windows"
- fail.
I suspect some kind of type differences between ADOR. RecordSet
implementations on Vista and XP. Question is - how to get around that problem.
Any help?
Thanks

As an addition to the way of calling server side obect:

Public Function OpenObject(strSBO As String, strServer As Variant) As Object
..................
Dim rdsDataSpace As Object
Dim objSBO As Object
Set mobjRDS = CreateObject("RDS.DataSpace")
mobjRDS.InternetTimeout = 0

'Use the dataspace CreateObject method to instatiate remote object
Set objSBO = mobjRDS.CreateObject(strSBO, strServer)
Set OpenObject = objSBO
....................................
End Function