How come yahoo messenger doesn't let me sign on?

I have my sn and password saved on the computer, and i sign on to yahoo messenger after i sign in online everyday. Today, however i couldn't sign on, regardless of what i did. I even uninstalled yahoo and then reinstalling everything. I even changed the password to make sure it isn't b/c of wrong password. It says yahoo was unable to connect, exactly what does that mean? I tried changing the proxies setting, that was of no help...someone help...i have run out of options...help please!How come yahoo messenger doesn't let me sign on?first delete your cookies and temp files and offline content in internet explorer from, tools, internet options under general. what you need to do is uninstall yahoo 7.5 or 8.0 beta from your add remove programs{ in your control panel} {the tool bar and mail all of the files for yahoo that you see there} then also go to your c drive and open, go to program files, open, then go to yahoo folder at the bottom, open, then delete messenger folder {witch has the cache file in it} if it says you cant delete the whole folder it is ok open it and delete everything that you can. then go to http://www.oldversion.com/program.php?n and download 7.0 run the installation, follow the direction perfectly but do not download tool bar or set as your homepage it will ask if you want only messenger nothing else , then your computer will restart, and then try to log on, it might give you an error for no connection, go to above the smiley and click on the messenger preference tab and pick no internet detection button this will fix your problem have a good night :P let me know if it works im at tlattero@hotmail.com :P 7.5 has a runtime error in it which causes your com to stop logging on and 8.0 was not compatible for my com at the time i tried to download it i noticed the problem when i tried to repair 7.5 got a message saying that it couldnt find the correct path to a dll file so i tried 8.0 and no such luck said i was logged on to two computers and keeped logging me out it aint a power outage it is a program malfunction. with both 7.5 and from what i can tell 8.0 beta version for now untill yahoo can get the chance to fix the problems this is only a quick fix. myself and the 30 some people who have already tried and it helped remember please you will lose your archives cause it is a new program but you will still have the same account and friends.How come yahoo messenger doesn't let me sign on?I have problems with yahoo messenger too...soi don't think is your computerHow come yahoo messenger doesn't let me sign on?it could be temporary service problem. try signing in againHow come yahoo messenger doesn't let me sign on?Have you checked your isp folders and files for errors? Look forthose that are labeled Unknown device. and change them to the correct properties. then defrag and restart. other wise folow the second answers methiod that should get you back up and running.