You need to reformat the drive, probably. It probably comes pre-formatted as FAT32, which is primarily used under Windows.
Open Disk Utility (Applications > Utilities > Disk Utility) and select the Porsche drive in the left-hand sidebar. Then, click the "Partition" pane, and select how many partitions you would like under "Volume Scheme" (usually just one unless you need to "split" the drive into different partitions). Name the drive, and choose "Mac OS Extended" or "Mac OS Extended (Journaled)" (the latter is preferrable) and then click the "Partition" button at the bottom.
This will erase the drive completely and put the proper format on the drive for use with your Macintosh (and only Macintosh, so the drive will not be compatible with PCs). That should solve the filename problem you're experiencing.
Be sure to get all the data on the drive back off of it, as this procedure will completely wipe the drive clean! Good luck, let us know if that fixes it!