This is a common problem on PVRs. I had it on my Topfield 7000 when I had one, and Beyonwiz PVRs are similar, and though their padding priority setting gives you some control over the point at which it switches from one recording to the next on the same service, you still almost always get a bit of one program in the wrong recording. Both the Topfield and the Beyonwizes allow you to play recordings one after the other, but on both you get a short (~1sec) gap in the program where the switchover occurs. The more recent 4-recordings-at-a-time Topfields may handle this better.
I don't know whether the Humax allows the selection of a sequence of recordings to play in one go.
In theory, the broadcast Now/Next information should be able to trigger the correct switchover from one program to another, but the accuracy of the broadcast information there seems
not to be all that good (fairly long discussion on DTV forum), either.
Anyway, there's not much that IceTV could do to help apart from allowing sequential recordings on the same service to be rolled into a single timer (this has been suggested a number of times on the forum). Then there are problems with naming the recording. The only real solution is for broadcasters to actually stick to their schedules, and allow some slack between the end of one program and the start of the next (e.g. ad break, station promo). But I don't see that happening real soon.

ABC and SBS do tend to be a bit better at sticking to their schedules, and they do have breaks between shows for promos, ads (SBS) and news updates, so the problem tends to be bigger on commercial services.
The largest program overrun I've ever seen was a Big Brother final that went 50min+ over time. I only know because I wanted to watch whatever followed it. Honest
