It seems that by default, the Windows XP Remote Desktop Client does not support Network Level Authentication (NLA), which is what our 2012 servers demand.
Fortunately, there is a quick fix to the problem. All you need to do is add a couple of registry entries, restart your computer, and you’re away. The entries are as follows :
In regedit.exe, select the following key :
Within this key, there is a REG_SZ value called “SecurityProviders”, which contains multiple comma separated values. At the end of this string, add a comma and “credssp.dll” :
Click OK, then select the following registry key :
Within this key, there is a REG_MULTI_SZ value called “Security Packages”, which contains a list. At the end of this list, add “tspkg”.