Series 1 TiVos run on standard Linux, and use software for Daylight Savings.
Series 1 DirecTiVos (same platform, made for DirecTV) have had their software upgraded with the DST Fix.
Series 1 TiVos will still function partially, but will have the wrong date/time during the time between old DST and new DST. This will cause all manual season passes to break, and make the manual guide wrong.
This is getting close to boat anchor mode... time to upgrade to a DVR PC?
Discussion at the TiVo Community about the Non-Upgrade