I am having two problems with my Mac that I hope someone here will be able to assist me with. It is a late 2010 Macbook Pro, Intel Core i5, 8GB memory. Currently, it has a single partition running 10.6.8. (For several months, I had two partitions on the hard drive: the primary partition running Snow Leopard, and a smaller partition running Yosemite, so it is Yosemite capable). 1) The first problem is that Ive tried to update to Yosemite on the entire hard drive, but have been unable to complete a successful download of Yosemite from The App Store. I have tried twice now, and each time I get the notice The Application could not be downloaded. The application you tried to download could not be downloaded. Check you internet connection and try again. 2) As a second option, I have tried to do a clean install of Snow Leopard on a single partition, but am unable to accomplish this either. The internal optical drive has not worked for some time, but I have an external optical drive; in addition, Ive created SL installation discs on both a USB flash drive and an external hard drive. The problem is that NONE of these appear to installing. When I reboot and hold the Option key, each will appear - for example, if I have the USB flash drive plugged it, it will appear as a hard drive that I can select - but when it is selected, NOTHING happens. I get the Apple logo, but it is clear that no files are being copied to begin the installation process. The same thing happens with all three: the flash drive, the external hard drive, and the external optical drive. Ive checked the hard drive with Disk Utility and it appears to be fine. Any ideas?