TortoiseSVN no longer remembers password

In my workplace, we've been plagued with this issue since switching from http to https (maybe a year ago). At least, I think that's when it started. Whatever the reason, TortoiseSVN constantly forgets my svn credentials. I want to get to the bottom of why.

Here is the interesting bit - it can't really be tortoise' fault, as it clearly still knows the password based on the following behavior:

After it prompts you for the password that you had it remembering (that you had told it to remember previously), if you hit cancel and try your commit again, it won't prompt and it will work. Clearly the credentials remain stored, but some client/server interaction causes it to fail to authenticate sometimes. This happens very frequently. Most of us don't even bother checking the box anymore. (which would be a better practice from a security standpoint, but we all have our faults)

The moving parts:

• Subversion 1.5.x Server
• Apache 2.x
• TortoiseSVN (1.5.x)
• Active Directory (our authentication is against our standard AD credentials)
• HTTPS

I am sure there is a solution out there. I will keep this post updated as I progress...