PaPCo is not a professional package designed to be fool-proof and un-crashable. It is designed for the intelligent user who has some idea of what it can do and what not. It is very likely that the user can come up with many things that PaPCo cannot do, and since we haven't thought of them, there is probably no check against you trying, and PaPCo will crash. Error trapping in PaPCo is only performed at the points where user-written functions are called, if PaPCo crashes elsewhere then there is a problem with PaPCo core.
The PaPCo main core is very stable by now with most of the bugs out. But as new modules are written they are also a source of new errors: they, however, are the problem of the module author. Most new problems crop up in the modules and the individual plotting routines, and most of those are due to a violation of the PaPCo naming convention.
If you make changes and add to PaPCo, PLEASE do this in your modules. DON'T touch the main core of PaPCo: this would make any maintenance by us at LANL very difficult. If you absolutely need a change that affects the core of PaPCo, contact us here and we will try to add the change and include it a the next version of PaPCo. In fact, this is how the package has progressed, thanks to the many useful suggestions by users.
PaPCo has been in use and running since May 1995 and as problems are encountered they are fixed. So as we go along it will get better and better, and more functionality will probably be added in subsequent releases.