A range check error is casued by 1 of 2 things 1) a DATA Problem or 2) a memory Problem. To test which is the issue try this. Try to make the range check error occur on a second PC on your network. if it does not occour in the same place as the first machine it is a memory problem. Reboot the mahchine that has the RANGE CHECK ERROR. that will fix it.
If the problem DOES occour in the same place then it is a data problem. You need to back everyone out of RPRO and reconstruct the data. so if the problem is occouring in customers you need to reconstruct your CLIENT.DAT file.
If you need help reconstructing, check our website www.bighairydog.com go to the support link and choose the self training videos. there is a video that walks you through recontruct. check them all out while you are there, they are FREE!
Hope that helps