Cannot Set Default Printer

Something happened to my system and it can no longer recognize a default
printer. I get an error message "Cannot Set Default Printer," and I have
trouble adding new printers as well. I have an hp color LaserJet 5500 with
Windows Vista Home Premium. It's been working ok until now. Don't know
changed it. (Several programs such as Adobe Reader, Quickbooks and others
can't print without a default printer being set).

I think the inability to set a default is also the cause of why I can't link
to programs either. I get this message: "Windows cannot access the specified
driver, path or file. You may not have the appropriate permission to access
the item." I have full control, so I can't figure that out.

I'd really appreciate any help anyone can offer.

Thanks in advance.

verify you have write access to
HKEY_CURRENT_USER\Software\Microsoft\Windows
NT\CurrentVersion\Windows\Device

The default setting is write is enabled. I do not know what application is
changing this setting.

Thanks, Alan, but there is no "Windows\Device" under CurrentVersion. The
only key there is "Winlogin". And I do not have the requisite permission to
set up a key under CurrentVersion.

What do I do now?