I should feel lucky. I've debugged and fixed program crashes, which were induced by garbage collection. It have taken only 4 days. I've added 5 lines to the program, and 8 problem issues go away, and more issues will be closed after testing.
The main problem during debug was to identify the source of the bugs. I managed to find the reason on the third day. It was Guile garbage collection.
For those who is using Guile and getting
freed cell %p; GC missed a reference
You are lucky to find this note.
If you store Guile values in heap, make sure that the garbage collector can find them. If not, use the function "scm_gc_protect_object".