How many partitions on the system?
Have you contacted the persons who worked on your system?
You are having trouble only with the G: partition?
You can go to disk management (Start/Run...type diskmgmt.msc and hit Enter) and see what status (if any) is displayed there for your G: partition. Post the details here, please.
You can also check Event Viewer for errors. You are interested in any error referencing a disk or drive (e.g., Disk 0). If you have any, post those details here.
How To Use Event Viewer - http://www.bleepingcomputer.com/forums/t/40108/how-to-use-event-viewer/