Id suggest delaying the network login and increase the amount of times it attempts before it fails. Be sure you have a valid WINS address in your TCP/IP settings. If the Secondary WINS is blank, add the primary WINS server here again. This delays the network login about 4 additional seconds. If its still not enough time or you truly have 2 valid WINS Servers, edit the Windows 98 registry key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP
NameSrvQueryCount and bump the value (in milliseconds) from the default of 750 to maybe 1500 or even 2500. Finally, check HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netlogon\ and add a DWORD value named ExpectedDialupDelay. Set this value to a decimal number (in seconds), 1-6000. Usually 10-20 is good but you might want to be liberal here. Good luck!