Hey Steve
Just wondering where you say "current one is set to 5.x "... is that the DW setting for PHP or the actual web server running version of PHP?
I have come across some weird errors, and after an Un-install ... reboot of PC, and then a Re-install of ALL extensions has settled some problems.
You may want to download the extensions again as well, as maybe there is a corrupt file there...
Just a suggestion...
Tony