(Preliminary aside.) How do you know if Adobe Reader is "integrated" with your browser as a "plug-in?" One very simple way is to click a link to one of the newsletter pdf's. If the Reader immediately starts up in the browser's window and begins opening the newsletter, then it is running as a plug-in. If, instead, you see the familiar download dialogue box (what should I do with this file? open it or save it to disk?), then the Reader is not integrated with the browser.
There is ample discussion of problems people have experienced when using the Reader as a plug-in to their browsers, especially to MSIE. A web search for Adobe Reader plugin problems will steer you to a fuller discussion of possible causes and remedies, if you are curious.
My suggestion is simply this: If you are able to click the link to a newsletter and if the newsletter opens successfully and you are satisfied with accessing the newsletter that way, then do nothing else. If you have a "late model computer" with adequate RAM, this should almost always be the case.
But if you experience any of the following problems: freeze-up and locking of your system, pages missing from the newsletter, blank pages, or inability to save the newsletter to your hard drive, then I recommend that you run the Reader only as a standalone program and not as a plug-in to your browser. Undoing the integration of the Reader with the browser is not terribly difficult ... click here for instructions. If this is how you decide to operate, then make yourself a Newsletters folder, download the newsletters and save them to that folder. Then to read a newsletter in that folder, just click it open.
Did I mention the advisability of staying current with browser releases? Kindly read this and then read the pointed comments about browsers in the about this website page and take them to heart. If we cannot spare a few minutes to keep our basic software current then, (sigh), the terrorists will have won.