The latest Metatrader official build 920 is apparently not quite compatible with previous versions.
The custom indicators and scripts compiled by the previous versions do not seem to be compatible with the 920 and refuse to load. On the other hand, scripts compiled by the latest compiler from build 920 do not seem to run in previous versions below build 910.
For temporary fix I created double versions of download. The regular download should work with the latest build (920), while Alternate Download should be compatible with older builds down to 840.
In case of continuing problems roll back to 910.
A new build 940 has been released by Metaquotes, which seem to be stable again and should fix the known glitches.