I'm submitting this answer because it isn't here.
ADOBE Flash's Houdini Disappearing Act: A POSSIBLE FIX
The Yahoo Answers (2) regarding Adobe Flash's disappearing aren't applicable, up-to-date and don't fix the problem. It's very frustrating when you install Adobe Flash, again and again on every audio or video sight, then poof and poof, it's disappeared again! My frustration level turned into extremely annoyed quickly. This cost me, not only frustration, but also time and money, as other internet commenters mentioned, too.
It's taken me many hours to search the Internet for the right answers to fix this problem. I hope others can avoid this grief. And thanks to the two people who each offered one-half the fix in two different postings. The individual suggestions didn't work for me, but using both "fix it ," suggestions together, worked. I hope it works magic for you, too.
Using Windows 7 and IE, two tasks must be completed to prevent Adobe Flash from disappearing on various websites and your folders, even though you know it's loaded on your computer. You must change permissions in Adobe Flash and change settings on your anti-virus protection to prevent this. Adobe updates also may change your settings, which may require you to make one or both these adjustments again. Not all software updates affect Adobe Flash. IE and anti-virus updates, most notably also sometimes cause issues with other software programs that must be uninstalled and re-installed.
Adobe Flash: Click on Start, Computer, C: Programs x86) file folder, Adobe Folder, then right click the Adobe Flash folder. In the pop up box, called "Flash Player Properties," under the General Tab, make sure the "Read Only" box is highlighted. Now, click on the Security Tab. In the top half of the box is a list of users. Click on one to highlight it. Your list may be just yourself, or may include more, Owner (as yourself/other), Administrator or System. In the bottom half of the box, a list of permissions appears. The owner, administrator, or named PC/Owner should have full control, with checks on all items in the "Allow" column, except Special Permissions at the bottom that should be grayed out. Now, click on the Advanced button below the bottom part of the box. A new box appears, called, "Advanced Security Settings for Flash Player." First look at the , "Effective Permissions" Tab, so you know what the available allow or deny items are. Don't change items on this tab (it's highlighted, so you may not be able to change it). It grants Adobe full control to update your flash software, which sometimes requires them to change and/or delete files. Now, click on "Permissions" Tab. A list of users comes up. For anyone on your user list other than owner/yourself, administrator, including System, and others accessing your computer, click on the button at the bottom that says, "Change Permissions." For System, make sure the two boxes, "Delete Sub-folders and files" and "Delete" are checked under the "DENY" column on the right. This helps keep other incompatible programs from deleting Adobe Flash Player.
Anti-Virus settings: In Avast, open the program, click on Real Time Shield, then Script Shield and click the STOP button.
For other anti-virus software, you are looking for a similar security setting that is blocking web sites from accessing Adobe Flash on your computer. You may need to do an Internet Search for settings help for other Anti-virus software programs that you use, or contact their support team for assistance. If you are using utilities maintenance programs, you also may need to add Adobe Flash to the "exceptions" screen to prevent it and it files and sub-folders from being deleted.

