BleepingComputer.com: 'no operating system' msg; and multiple ip addresses

hi, first post.
dell studio 1747, win 7 pro x64, intel i7 1.73, 8gb ram, norton int. security; 4 computer home network, protected linkysys router

a while ago the computer would suddenly slow extremely, almost freeze. i would power off and restart until that occurred again, then repeat. after some weeks (?) the computer made some croaking sounds and froze. on powering up after the initial screen shot w/bios and setup, a black screen with 'no operating system' appeared. using windows repair disc via cd boot, no problem was found, so i retrieved a recent image from the backup lacie drive. when rebooted, the same 'nos' appeared. using a norton bootable recovery disc i am able to write this on the computer and do all functions, and i find that the image of a few days ago is what i'm working with. the computer can still slow and almost freeze at times

i ran full norton scan including rootkit (tho on reboot had to go from the recovery disc) and norton power eraser, as well as malwarebytes, with no infection found.

once before and this am i received a msg that windows detected an ip address conflict, that there was another computer on the network with the same ip address.

when i look at the network connections i see all 4 of the computers including this one. none share with this one. the other three show a single ip (related) address to one on my computer. however, mine shows 2 additional ip addresses if i look at my wireless connection: 1) fe80::90e:52a1:4d29:330%15 (which makes no sense to me), and 2) 169.254.3.48, which on whois lookup says this is a 'link local' - rfc3927 -IANA -reserved...'allocated for communication between hosts on a single link'.(the iana or internet assigned numbers authority is in marina del rey, ca).

if i hook hardwired to the router/lan and look, the iana ip is not there, and this different one from the first above is present (along with my regular one related to the other three computers): fe80::69be:f952:344b:3ee%10

when i look at the norton security history it appears that protection is being removed from the wireless and lan adaptors and new connections made. (i have yesterday made restricted my default on new connections where able to.) some of this morning's are, sequentially:

at 6:30 when i woke it from 'sleep':

ip address has disappeared from adaptor dell wireless 1387 minicard and is no longer being protected: ip address: 192.168.1.102 (my computer)
" " : " : fe80::90e:52a1:4d29:330%15
protecting you connection to a newly detected network on dell 1387 : : 192.168.1.102
" " : " .104
" " : " .103
" " : fe80::90e:52a1:4d29:330
" " on realtek PCIe GBE family controller : fe80::69be:f952:344b:3ee3
" " on adapter 'teredo tunneling pseudo-interface' : fe80::c86:1b9:EF57:FE97
" " "" "" : 2001:4137:9e76:c86:169:3f57:fe97

at 6:31am:
" " on realtek pcie gbe controller : 169.254.62.227 (??iana)
" " " " : 192.168.1.105
firewall rules automatically applied for applicaation layer gateway service (program path: windows\system32\alg.exe; local computer (192.168.1.105) 49182; traffic: inbound tcp, port 49182 (protected status)
all connections again disappear and new ones come up as above
connected to restricted network ( 00 0F 66 CA CB F7)

7:47 all addresses again disappear
7:54 access to thread data blocked x2 (actor: w\sys32\services.exe)(actor pid: 604)(target: programs\nis\engine\186.0.29\ccsvchst.exe)( target pid: 4368 and7040)

i have been offline as i write this, will connect and send. any help would be most GREATLY APPRECIATED!!! i imagine i could use the original dell restore and restore all my files from backup and reinstall everything (??), but it
sure would be better if i don't have to; and i would of course worry that something like this could/would occur again.
Thanks.
buol