Error when using sum function in rows

[jflux]

I'm a long time excel user, but something odd is now happening to data I'm summing across rows. I have columns but sum across rows for total of labor and material. When I go to move column data B out of the sum range in column C, =sum(A1:B1) the sum column C changes as shown. below. And every time I move the number it keeps changing?? Have I changed some setting, I've been doing this for years, perplexed.

<TABLE style="WIDTH: 168pt; BORDER-COLLAPSE: collapse" border=0 cellSpacing=0 cellPadding=0 width=224><COLGROUP><COL style="WIDTH: 42pt" span=4 width=56><TBODY><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; WIDTH: 42pt; HEIGHT: 12.75pt; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8" height=17 width=56 align=right>50</TD><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; WIDTH: 42pt; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8" width=56></TD><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; WIDTH: 42pt; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8" width=56 align=right>500</TD><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; WIDTH: 42pt; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8" width=56 align=right>50</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8" height=17 align=right>50</TD><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8"></TD><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8" align=right>300</TD><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8" align=right>50</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8" height=17 align=right>50</TD><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8" align=right>50</TD><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8" align=right>100</TD><TD style="BORDER-BOTTOM: #d4d0c8; BORDER-LEFT: #d4d0c8; BACKGROUND-COLOR: transparent; BORDER-TOP: #d4d0c8; BORDER-RIGHT: #d4d0c8"></TD></TR></TBODY></TABLE>

 

[Aladin Akyurek]

Care to indicate the before form and the after form, and what after form should be?