VBScript prime number generator

  This is a really cool HTML application which finds all the prime numbers in a given range. This program is pretty fast for low ranges and may raise the core usage to 100 or 90 percent for very large ranges. So I prevented large ranges from being entered as it caused some errors and caused the computer to crash.
The VBScript used in the program is really simple. The program tries to get a integer number by dividing it with all possible numbers and if does not get an integer the number is confirmed as a prime number. This process is repeated for all the numbers in the given range.
To make the program paste the following code in notepad and save with a .hta extension.

<html><head><title>PRIME CALCULATOR</title><HTA:APPLICATION APPLICATIONNAME="PRIME CALCULATOR" ID="PRIMECALCULATOR" VERSION="1.0" MAXIMIZEBUTTON="no" SCROLL="no"/></head> <script language="VBScript"> Sub Window_OnLoad Dim width,height width=500 height=475 self.ResizeTo width,height RID.value = 0 End Sub Function PVal If (BTN.value = "Stop") Then SID.value = 1 Else If (boxa.value = "" Or boxb.value = "") Then MsgBox("Enter a range!") Else If ((boxa.value = boxb.value) Or (Int(boxa.value) > Int(boxb.value))) Then MsgBox("Are you mad? Enter a valid range!") Else If (Int(RID.value) = 1) Then RID.value = 1 Else boxa.readonly = True boxb.readonly = True PSet() End If End If End If End If End Function Function PSet If (boxa.value <= 0) Then boxa.value = 1 Else End If code.value = "" count.value = 0 anum.value = boxa.value bnum.value = boxb.value BTN.value = "Stop" SID.value = 0 RID.value = 1 ID.Value = 1 PStart() End Function Function PStart anum.value = Int(anum.value)+1 If (Int(anum.value) = Int(boxb.value)) Then PStop() Else If (SID.value = 1) Then PSStop() Else calculate(Int(anum.value)) End If End If End Function Function Calculate(num) chk = 1 rmn = 1 Do Until chk = num-1 chk = chk+1 rmn = num Mod chk If (rmn = 0) Then Exit Do Loop If (rmn = 0) Then code.value = code.value Else code.value = code.value & ", " & num code.doScroll count.value = count.value+1 End If Do While ((Int(ID.value) = 1) And (Code.value <> "")) code.value = Replace(code.value, Left(code.value, 2), "", "1", "1") ID.value = 0 Loop Junk = SetTimeOut("PStart()", 1) End Function Function PStop BTN.value = "Calculate" Junk = MsgBox(count.value & " prime numbers found between the range " & boxa.value & "-" & boxb.value & "!", 64, "INFO") ID.value = 1 RID.value = 0 boxa.readonly = False boxb.readonly = False End Function Function PSStop BTN.value = "Calculate" ID.value = 1 RID.value = 0 boxa.readonly = False boxb.readonly = False End Function </script> <body style="font-family:BookMan Old Style;"><input type="hidden" id="RID"><input type="hidden" id="ID"><input type="hidden" id="SID"><input type="hidden" id="count"><input type="hidden" id="bnum"><input type="hidden" id="anum"><table align="center" border="1"><caption><hr><b>PRIME CALCULATOR</b><hr></caption><tr><td>Enter the range of prime numbers you want and click Calulate to get all the prime numbers in that range!<hr></td></tr><tr><td align="center"><input type="text" id="boxa" size="10" onkeypress="If (window.event.keycode < 48 Or window.event.keycode >57) Then window.event.returnvalue = False"> To: <input type="text" id="boxb" size="10" onkeypress="If (window.event.keycode < 48 Or window.event.keycode >57) Then window.event.returnvalue = False"></td></tr><tr><td align="center"><input type="button" id="BTN" value="Calculate" onclick="PVal"></td></tr><tr><td align="center"><textarea wrap="virtual" id="Code" cols="52" rows="12" readonly>