can't import .pfx in XP Home

I have two working certs generated on my wife's computer (XP Home), successfully exported as .pfx and transferred to my computer (XP Home) and successfully imported into Mozilla Firefox and Thunderbird, but only for testing purposes. I use IE/Outlook Express. I can't get the Certificate Wizard to import either .pfx file, trying for over a week now and losing hair. I keep getting the error: "Internal error occurred. The private key that you are importing might require a cryptographic service provider that is not installed on your system."

1) Have turned off windows firewall.
2) Uninstalled AVGFree, AdAware, and SpyBot
3) Uninstalled SQLServer
4) Tried to upgrade IE7 to IE8, but constant crashing of IE8, restored IE7
5) Downgraded IE7 to IE6
6) Set permissions on %Me%\applicationdata\microsoft\crypto\rsa\machinekeys folder for everyone, "me", administrator, system to full control for this folder, subfolders, all files, turned off inherit permissions, turned on the child permissions box
7) Tried deleting the HKLM\software\microsoft\cryptography\providertypes\type001, and needed to reactivate windows by phone!
7b) Tried changing \type001\name to microsoft enhanced cryptographic provider v1.0 or to microsoft base cryptographic provider v1.0, and deleting the "typename" key
8) Have tried certmgr.msc

Any other suggestions?