Steve - over the last few days I have had a similar issue. I have two DSL lines from Frontier. MY primary line is fairly stable but my secondary line is not. I loose connectivity during the evening hours. There are times that I can pull PPP connection but will not pull an IP address. Then there are other times where I am not even able to pull a PPP connection. To set others minds at ease, I have three spare modems and they all exhibit the same problem and they all work without issue on my primary line. They are currently working the issue.
Put a call into Frontier, just give them the symptoms and don't add anything else to the report. Let them work the issue. You will, more than likely, have to become a squeaky wheel.
I'm glad someone else had this issue, but yet it's not good that we are having this problem. It just happened today this morning. My PPP seems to always be down.
I wish I could call FTR but its my moms job to do that.