numerous errors showing up in event log

I just typed this and got an error message, so I apologize if it shows up twice! In the last couple of months I have had numerous errors showing up in the event log. Since around the middle of November, I have had hung application errors involving Internet explorer (30 + times), Windows explorer (40 + times), photoshop (35 + times) and other applications 1-5 times. MCMISPUPDMGR shows up 35 + times with the message that it cannot be found. I cannot find anything in the microsoft data base concerning this application nor do I know what it is. The first of January I ran the deep cleaning steps as listed on this site. I have ran chkdsk and defrag on both my c drive and my external hard drive. No bad sectors were found on the c drive, but 416(I don't remember how they were listed) were found on my external drive. I have a lot of large photo files on my computer so I do understand about Photoshop hanging up sometimes. Here are my computer specsavilion 763N, 2.53 ghtz Intel Pentium 4 processor, 512 mb DDR Sdram memory, 80 gb hard drive w/50 gb free, and a 160 gb hard drive with 40 gb free. I would appreciate your help with getting my computer straightened out so that I can use my computer instead of fixing it! Thanks, Diane