I've recently installed updates to both ACR 5.6 and 5.7 to Photoshop CS4 running under Windows XP. I've done this by downloading the updates and applying them directly and by doing it through Help>Updates in Bridge. It says that it has installed successfully. However, the ACR icon is not highlighted in Bridge and I cannot open any .PSD or .FFF files in ACR (no problems opening them with Photoshop). It previously worked with PSD files, and I have installed the Hasselblad FFF plug-in since it last worked.
Any ideas what might be wrong ?