Rumors about the new patch 1.24 and its incompatibilities with other maps are all around the internet, forums and etc. In this case, nothing better than a word from IceFrog about what is really going on with the new patch and DotA.
Those who were waiting for the stable version of the actual DotA map 6.61b will have to wait a little. Now, IceFrog is concentrating his efforts on fixing the map to work properly on the 1.24 patch and the first step is done: he launched the version 6.61c of DotA as a "fast solution" for the incompatibility. There is no difference between 6.61b and 6.61c.
The problem is that 1.24 may not be the last patch. Probably, 1.24b and 1.24c will come too and even if IceFrog is able to fix the DotA map in the near future, we will have to wait until Blizzard fixes the WarCraft. For example, some people are facing problems using the WarCraft Editor with the 1.24 version.
Now you are asking "Why 1.24?". Well, the most important thing to be fixed is the possibility of downloading viruses intead of downloading maps when you join a host with an unknown map. But one thing is good: the new patch gives the opportunity of building custom maps up to 8MB size (instead of the actual 4MB limit). Who knows what IceFrog will develop for the future versions...
IceFrog
As of right now, 1.24 still has various bugs in it's functions that prevent most 1.24 maps from running properly on it. As these issues get fixed in coming 1.24b/1.24c patches, 6.62 beta will be updated alongside them. As soon as the new patch is stable and 6.62 is tested on it sufficiently, it will be released. Hopefully the map will return to a stable code state in the very near future.
To finish the discussion, there is nothing we can do but report to IceFrog any bugs that you face when playing DotA and wait for him to fix everything. He is really giving his best to go through this problem as fast as he can.