A rare but possible problem that can occur with long running programs:

Holier Than Thou

by Tony DaSilva

From the article:

Since C++ (by deliberate design) does not include a native garbage collector or memory compactor, programs that perform dynamic memory allocation and de-allocation (via explicit or implicit use of the “new” and “delete” operators) cause small “holes” to accumulate in the free store over time. I guess you can say that C++ is “holier than thou“. :( ...