Unicows.dll is the Unicode Layer DLL for Windows 9x and ME. Unicode is a standard for representing characters as integers. Unicode uses 16 bits rather than the ASCII standard of 7 bits to enable more than 65,000 unique characters to be represented. As a result, languages such as Greek, Chinese, and Japanese are able to be supported.
My experiences with Win98 (a whole lot) says that the 98 kernel lasts a couple of 2 or 3 years, then a reformatting is usually in order. Go here for instructions:
http://www.worldstart.com/tips/shared/rr1.htm
...muck, May 2006