My guess is Rhumbas VTP1 fixer might work. Dick discovered a problem with the VTP1 code, his fixer changed all instances of "0" location points to "1", & it removed the artifacts with "handed" vtp1 lines (eg shorelines), maybe the fixer works similarly for VTP1 polys too?
As a habit I've always used Dick's VTP1 fixer on any VTP1 reef polys I've made with G2K, just in case.
Another cause might be just having 2 points created too close together. Again, my experience is mainly with VTP1 lines in G2K, & sometimes on compile you can get wierd sharp "spikes" appearing when 2 points are too close to each other (influenced by the width of the line). And these VTP1 lines are just narrow VTP1 polys after all ....