Here is my un-personalised prefs file for Pagestream4.prefs

=== START ===

PREFERENCE FILE
USERNAME "ME - Your own details to be known as"
USERCOMPANY "Home or work address - your choice"
USERREGNUM 6DIGIT
USERPASSWORD 4S5uPlide
RECENTFILES Documents/yours/wherever.pgs
SETDIMENSIONS 8.2677" 11.6929" SINGLE PORTRAIT
SETMARGINGUIDES 0.5" 0.5" 1" 1"
SETCOLUMNGUIDES 2 0.25"
DISPLAYDPI 72 72
SHOWMEMORY TRUE
SHOWDATE TRUE
SHOWTIME TRUE
CENTERONDCLIP TRUE
SETFONTCACHE 100 50 OPENFONTS 50
SETFONTPATH PageStream4:Fonts
SETUNDOLEVELS 60
SETREVISIONTRACKING OFF
SETBACKUP AUTOSAVE OFF AUTOBACKUP ON COUNT 3 PATH Documents/Backups
SETSMART DASHES ON BULLETS ON SINGLEQUOTES ON DOUBLEQUOTES ON
CHARACTERSET Amiga
SETFONT Triumvirate-Normal
SETTYPESIZE 12pt
SETTYPEWIDTH 100%
SETLANGUAGE British
SETPARAGRAPHSTYLE
SETCHARACTERSTYLE
SETALIGNMENT LEFT
SETBOLD OFF
SETITALIC OFF
SETUNDERLINE OFF
SETOUTLINE OFF
SETREVERSE OFF
SETSHADOW OFF
SETSMALLCAPS OFF
SETSCRIPT OFF
SETTRACKTABLE NORMAL
SETTRACKING 0%
SETLASTLINEFLUSH 0cm
SETTRACKRANGE -10% 0% 20% 80% 100% 130%
SETLEADING RELATIVE 120% MAINTAIN OFF
SETBASELINELEADING RELATIVE 80%
SETINDENT NONE
SETFIRSTLINE NONE
SETPARAGRAPHLEADING BEFORE NONE AFTER NONE
SETRULEABOVE OFF
SETRULEBELOW OFF
SETNUMBERED OFF
SETBULLET OFF
SETDROPCAP OFF
SETTABRULER
SETDEFAULTTABSTOP 0.847cm
SETHYPHENATION OFF
SETHYPHENLANGUAGE DEFAULT DATA 6 3 2 1
SETKERNING ON KERNABOVE 4pt
SETLIGATURE ON ANY -20% 20%
SETHANGING ON
SETOPTICAL ON
SETMEASUREMENTS COORDINATE CENTIMETERS SAMEAS RELATIVE SAMEAS TEXT POINTS FROM PAGE
SETDOUBLECLICK REQUESTER LINEFILL
SETDUPLICATEDEFAULTS 0.635cm 0.635cm
SETNUDGEDEFAULTS 0.2cm
SETLIVEUPDATE SCROLL OFF DRAG OFF
SETVIEWDEFAULTS SCALE FULLPAGE SCALERANGE 5% 3000% GRID SHOW SNAPTOGRID OFF DISPLAYGRID INBACK GUIDES HIDE SNAPTOGUIDES OFF DISPLAYGUIDES INBACK RULER SHOW PICTURES SHOW DRAWINGS SHOW OUTLINE SHOW TEXTLINKS HIDE INVISIBLES HIDE PAGECOLOR 255 255 255 PAGEBORDERCOLOR 0 0 0 PAGESHADOWCOLOR 170 170 170 PASTEBOARDCOLOR 230 230 230 GRIDCOLOR 0 0 0 PAGEGUIDECOLOR 0 255 255 RULERGUIDECOLOR 255 0 255
SETAUTOCOLUMNS OFF
FILEFILTER FALSE
SETPASTEINCENTER ON
SELECTONPASTE ON
SETDOCUMENTPATH Documents
SETTEXTPATH Text
SETGRAPHICPATH Graphics
SETSCRIPTPATH Scripts
SETSCRATCHPATH Documents/Backups
SETPDFPATH Documents
SETMAILMERGEPATH Text
SETPRINTPATH Documents
MAINTOOLBOX SHOW AT 0 42 VERTICAL
SETMAGNIFYINCREMENT 200% DRAGZOOM CENTER
SETCOLUMNDEFAULTS OPAQUE GUTTER 0.635cm
SETBOXDEFAULTS CORNER 0.318cm
SETARCDEFAULTS ANGLES 90° 360°
SETPOLYGONDEFAULTS SIDES 3 OFFSETANGLE 0° DEFLECTION 40% ANGLEDEFLECTION 50%
TOOLBAR SHOW AT 0 22
SETTOOLBAR NEW OPEN SAVEDOC PRINT PRINTSETUP EXPORTTEXT EXPORTGRAPHIC SAVEPDF SPACE INSERTPAGE DELETEPAGE MOVEPAGE CUT COPY PASTE PASTEASIS SELECTALL DELETE FONT SETSTYLE MAKEUPPER MAKELOWER MAKECAPITALIZED SPACE UNDO REDO SPACE LEFT CENTER RIGHT JUSTIFY SPELL LINKTEXT BREAKTEXTROUTING SPACE INDENTLEFT INDENTRIGHT HANGINGINDENT SPACE EXECUTE PREFERENCES SPACE LINEFILL INFORMATION
SCREEN Public 1280 1024 16 "Radeon9200: 16Bit 1280 x 1024" "Bitstream Vera Sans.font" 15
SETOUTPUT PostScript
SETOUTPUT1 SOURCE Tray2 PAPER A4 8.2639" 11.6944" 0" 0" PORTRAIT
SETOUTPUT2 PPD softlogik:printers/ppd/HP/HP5-ColorLaserJet_PS.ppd SENDTO DEVICE USBPAR:
SETOUTPUT3 CYANSCREEN DEFAULT DEFAULT MAGENTASCREEN DEFAULT DEFAULT YELLOWSCREEN DEFAULT DEFAULT BLACKSCREEN DEFAULT DEFAULT SPOTSCREEN DEFAULT DEFAULT
SETOUTPUT4 INCLUDEERRORHANDLER FALSE INCLUDEEOF TRUE
SETOUTPUT5 FONTUNLOAD DOCUMENT UCR 80% GCR 100%

=== END ===

Hope this helps, but I tried changing items in my prefs file, but it made no difference, so after changing some other prefs and other files and settings I eventually got Pagestream to work for me under MorphOS v3.1 originally I think it was.

Since then I have only needed to leave it in place when upgrading so haven't bothered, or needed to change anything about it, so it works really well, though there are the few occasional bits of weirdness that creeps in, but on the whole it functions very well.

I really hope you get it fixed, but just keep trying something different if this doesn't work, and eventually it will work. I wish I could tell you what it needs to get it to function properly, but I just cannot figure out exactly what it was that resolved my own issues with Pagestream 4, but as others have said it does work, and I just finished using it for the day a few minutes ago, under MorphOS v3.7..