File encryption certificate installation

[Rob Whythe]

I have a directory containing encrypted files on my Windows XP laptop in
order to keep some personal information private, which has worked well for
some time. Last week I joined my company network domain for a few days, then
reverted back to my usual workgroup, and found that I could no longer access
any of the encrypted files.

Having searched through the file properties, I was told by the system that
the CA root certificate is not trusted, and that I need to install the
certificate in the Trusted Root Certification Authorities store. The same
property sheet confirmed that I do have a private key that corresponds to
the certificate. I have been able to save the certificate in a '.pfx'
(personal information exchange) file, but I have no idea how to install it.
The 'help' info talks of installing it over a network, using tools I don't
have on my single-user stand-alone laptop, and the MSKB doesn't appear to
have any entries about this.

Can anyone point me in the direction of certificate installation
instructions, please?

Many thanks,
Rob

 

[Rob Whythe]

I seem to have stumped the group! ;o)

Next stage: I have reached the Certificate Authorities store (by running MMC
and opening system32\certmgr.msc), and have identified the previous
certificate in my 'personal' folder. I tried to install it in the Trusted
Root folder, both by dragging/dropping and by exporting/importing through a
file.

Drag/drop fails with the error: "The certificate cannot be pasted into the
Trusted Root Certification Authorities store. The RPC server is
unavailable."
I looked up 'RPC' in the services, and found that the RPC service was
running automatically, but the RPC Locator wasn't (set to 'manual'). I
started the RPC Locator but no change. I set it to 'automatic' and rebooted,
but no change.

File export/import fails with the error: "The import failed because the
store was read-only, the store was full, or the store did not open
correctly."
The file is not read-only, so the first suggestion does not hold. What the
other two mean I don't know.

Can anyone please suggest a way forward? I'm at a loss to understand what's
happening...