Digital BW, The Print

I have photoshop 7 and use windows 98.  I installed epson 2450 
scanner with twain driver and the twain5 driver works fine from 
photoshop using file/import-export.  I then installed silverfast se 
which came on my epson 2145 CD in the PS/plugin/import-export folder 
as directed.  When I try to use silverfast from file/import-export, 
the silverfast/lasersoft screen and logo comes up and 
says "searching  devices"  and then the computer freezes and I must 
use control/alt/delete to get out and I get the message photoshop not 
responding.  Any suggestions?  Thanks.