Think I found the answer for myself. I suspect the answer is that the drac card only reads FAT32 file systems so has a 4GB limit.  decided not to bother connecting via the DRAC just use the console redirect and a good old fashioned DVD. 
yesterday I updated the firmware of the DRAC 5 in the PE 1950 to version 1.65 A00. I then attempted to connect a Windows 2012 iso image but it kept failing with a spurious message of         The browser security settings do not allow filenames to be manually       typed into the textbox.       Click Browse to select the appropriate file. After trying to alter the IE settings, changing the path, truncating the filename, nothing worked and the above error was always displayed. I tried connection other iso images and have discovered that if an iso is selected that exceeds 4GB in size the above message is displayed. (the size limit may be smaller as the iso's i had were up to 2.5GB then jumped to 4.0GB+)  tried chrome but that fails to display the drac login page. tried firefox which attempts a JAVA connection that also fails. I have placed the site in Java's security site settings.  has anyone alse also encountered this size limit ? if so did you have a work around or do I need to burn a DVD and do it the old fashioned way.  Thanks in advance Bryden 
PE 1950 - Drac 5 - unable to connect iso image > 4GB